diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d009987
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+run_*
\ No newline at end of file
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..7d99d02
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,10 @@
+all: server client
+
+server: server.c utils.c
+	gcc server.c utils.c -o run_server -Wall -Wextra -pedantic -std=c11
+
+client: client.c utils.c
+	gcc client.c utils.c -o run_client -Wall -Wextra -pedantic -std=c11
+
+clean:
+	rm -f run_server run_client
\ No newline at end of file
diff --git a/client.c b/client.c
new file mode 100644
index 0000000..29a20cf
--- /dev/null
+++ b/client.c
@@ -0,0 +1,109 @@
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include "utils.h"
+
+#define PORT_NUMBER 8080
+#define SERVER_IP "127.0.0.1"
+#define IP_VERSION "IPv4"
+#define BUFFER_SIZE 128
+
+void connect_client_to_server(int client_socket_fd) {
+    // サーバアドレス構造体
+    struct sockaddr_in server_address;
+    int domain = (strcmp(IP_VERSION, "IPv6") == 0) ? AF_INET6 : AF_INET;
+    server_address.sin_family = domain;
+    // ホストバイトオーダーからネットワークバイトオーダーへ変換
+    server_address.sin_port = htons(PORT_NUMBER);
+    inet_pton(domain, SERVER_IP, &server_address.sin_addr);
+
+    // サーバへの接続
+    if (connect(client_socket_fd, (struct sockaddr *) &server_address, sizeof(server_address)) < 0) {
+        handle_error("Connection to server failed");
+    }
+}
+
+char* generate_request(const char *function, const char *query) {
+    // リクエストの生成
+    char *request = calloc(BUFFER_SIZE, 1);
+
+    if (strcmp(function, "calc") == 0) {
+        snprintf(request, BUFFER_SIZE, "GET /calc?query=%s HTTP/1.1\r\n", query);
+    } else {
+        handle_error("Unsupported function");
+    }
+    return request;
+}
+
+void send_request_and_get_response(int client_socket_fd, char *request) {
+    // タイムアウトの設定（10秒）
+    struct timeval timeout;
+    timeout.tv_sec = 10;
+    timeout.tv_usec = 0;
+    
+    // 送信タイムアウトの設定
+    if (setsockopt(client_socket_fd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout)) < 0) {
+        log_msg("Warning: Failed to set send timeout\n");
+    }
+    
+    // 受信タイムアウトの設定
+    if (setsockopt(client_socket_fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)) < 0) {
+        log_msg("Warning: Failed to set receive timeout\n");
+    }
+    
+    size_t request_len = strlen(request);
+    size_t sent_len = 0;
+    while (sent_len < request_len) {
+        ssize_t n = write(client_socket_fd, request + sent_len, request_len - sent_len);
+        if (n < 0) {
+            handle_error("Write to server failed");
+        }
+        sent_len += n;
+    }
+    log_msg("Request sent:\n%s\n", request);
+    char *buffer = calloc(BUFFER_SIZE, 1);
+    ssize_t bytes_read = read(client_socket_fd, buffer, BUFFER_SIZE - 1);
+    if (bytes_read < 0) {
+        free(buffer);
+        handle_error("Read from server failed");
+    } else if (bytes_read == 0) {
+        free(buffer);
+        handle_error("Server closed the connection");
+    }
+    buffer[bytes_read] = '\0';
+    log_msg("Response from server:\n%s\n\n", buffer);
+    free(buffer);
+}
+
+int main(int argc, char **argv){
+    // 引数の数をチェック
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s <function> <query>\n", argv[0]);
+        fprintf(stderr, "Example: %s calc 18+20\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    // ソケットの初期化
+    int client_socket = initialize_socket(IP_VERSION);
+    log_msg("Client socket initialized.\n");
+
+    // サーバへの接続
+    connect_client_to_server(client_socket);
+    log_msg("Connected to server %s:%d.\n", SERVER_IP, PORT_NUMBER);
+
+    // リクエストの送信とレスポンスの受信
+    char *function = argv[1];
+    char *query = argv[2];
+    char *request = generate_request(function, query);
+    send_request_and_get_response(client_socket, request);
+    log_msg("Request sent and response received.\n");
+
+    // ソケットのクローズ
+    close_socket(client_socket);
+    log_msg("Client socket closed.\n");
+    free(request);
+    return 0;
+}
\ No newline at end of file
diff --git a/server.c b/server.c
new file mode 100644
index 0000000..de51a15
--- /dev/null
+++ b/server.c
@@ -0,0 +1,193 @@
+#define _POSIX_C_SOURCE 200809L
+#include <errno.h>
+#include <limits.h>
+#include <netinet/in.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "utils.h"
+
+#define PORT_NUMBER 8080
+#define IP_VERSION "IPv4"
+#define LISTEN_BACKLOG 5
+#define BUFFER_SIZE 128
+
+volatile sig_atomic_t is_server_running = 1;
+
+void signal_handler(int signum) {
+    (void)signum;
+    is_server_running = 0;
+}
+
+void bind_socket(int socket_fd) {
+    // サーバアドレス構造体: sin_family, sin_addr, sin_port
+    struct sockaddr_in address_info; 
+    address_info.sin_family = AF_INET;
+    address_info.sin_addr.s_addr = INADDR_ANY;
+    address_info.sin_port = htons(PORT_NUMBER);
+
+    // ソケットのバインド
+    if (bind(socket_fd, (struct sockaddr *) &address_info, sizeof(address_info)) < 0) {
+        handle_error("Bind failed");
+    }
+}
+
+void listen_for_connections(int socket_fd) {
+    // 接続待機
+    if (listen(socket_fd, LISTEN_BACKLOG) < 0) {
+        handle_error("Listen failed");
+    }
+}
+
+int accept_connection(int server_socket_fd) {
+    // クライアントからの接続受付
+    struct sockaddr_in client_address;
+    socklen_t client_address_len = sizeof(client_address);
+
+    int client_socket_fd = accept(server_socket_fd, (struct sockaddr *) &client_address, &client_address_len);
+    if (client_socket_fd < 0) {
+        // シグナルによる中断の場合は-1を返す
+        if (errno == EINTR) {
+            return -1;
+        }
+        handle_error("Accept failed");
+    }
+
+    return client_socket_fd;
+}
+
+char* calculate_query(const char *query) {
+    // クエリの計算処理
+    // 例: "query=2+10" -> 12
+    int operand1, operand2;
+    char operator;
+    char *buffer = calloc(BUFFER_SIZE, 1);
+    sscanf(query, "query=%d%c%d", &operand1, &operator, &operand2);
+
+    char *extracted_query = calloc(BUFFER_SIZE, 1);
+    snprintf(extracted_query, BUFFER_SIZE, "query=%d%c%d", operand1, operator, operand2);
+    size_t extracted_len = strlen(extracted_query);
+    if (extracted_len > 0 && (strncmp(query, extracted_query, extracted_len) != 0)) {
+        log_msg("Malformed query: %s\n", query);
+        snprintf(buffer, BUFFER_SIZE, "Invalid query format");
+        free(extracted_query);
+        return buffer;
+    }
+    free(extracted_query);
+
+    switch (operator) {
+        case '+':
+            if ((operand2 > 0 && operand1 > INT_MAX - operand2) ||
+                (operand2 < 0 && operand1 < INT_MIN - operand2)) {
+                snprintf(buffer, BUFFER_SIZE, "Overflow error");
+                log_msg("Overflow detected: %d + %d\n", operand1, operand2);
+            } else {
+                snprintf(buffer, BUFFER_SIZE, "%d", operand1 + operand2);
+            }
+            return buffer;
+        default:
+            log_msg("Unsupported operator: %c\n", operator);
+            snprintf(buffer, BUFFER_SIZE, "Unsupported operator");
+            return buffer;
+    }
+}
+
+void handle_client_request(int client_socket_fd) {
+    // リクエストの処理
+    char *buffer = calloc(BUFFER_SIZE, 1);
+    ssize_t bytes_read = read(client_socket_fd, buffer, BUFFER_SIZE - 1);
+    if (bytes_read < 0) {
+        log_msg("Read from client failed\n");
+    } else if (bytes_read == 0) {
+        free(buffer);
+        log_msg("Client disconnected\n");
+        return;
+    }
+    buffer[bytes_read] = '\0';
+    log_msg("Request received:\n%s\n", buffer);
+
+    // /calc エンドポイントの処理
+    if (strncmp(buffer, "GET /calc?", 10) == 0) {
+        char *calculation = calculate_query(buffer + 10);
+        char *response = calloc(BUFFER_SIZE, 1);
+        size_t response_body_length = strlen(calculation);
+
+        if (strcmp(calculation, "Invalid query format") == 0 ||
+            strcmp(calculation, "Unsupported operator") == 0 ||
+            strcmp(calculation, "Overflow error") == 0) {
+            snprintf(response, BUFFER_SIZE, "HTTP/1.1 400 Bad Request\r\nContent-Length: %zu\r\n\r\n%s", 
+                response_body_length, calculation);
+        } else {
+            snprintf(response, BUFFER_SIZE, "HTTP/1.1 200 OK\r\nContent-Length: %zu\r\n\r\n%s", 
+            response_body_length, calculation);
+        }
+
+        size_t response_len = strlen(response);
+        size_t sent_len = 0;
+        while (sent_len < response_len) {
+            ssize_t n = write(client_socket_fd, response + sent_len, response_len - sent_len);
+            if (n < 0) {
+                log_msg("Write to client failed\n");
+                break;
+            }
+            sent_len += n;
+        }
+        log_msg("Response sent:\n%s\n", response);
+        free(response);
+        free(calculation);
+    } else {
+        log_msg("Unsupported request method\n");
+    }
+    free(buffer);
+}
+
+int main(){
+    // ソケットの初期化
+    int server_socket = initialize_socket(IP_VERSION);
+    log_msg("Server socket initialized.\n");
+
+    // アドレスの再利用を有効化
+    int optval = 1;
+    if (setsockopt(server_socket, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) == -1) {
+        log_msg("setsockopt SO_REUSEADDR failed");
+    }
+
+    // ソケットのバインド
+    bind_socket(server_socket);
+    log_msg("Server socket bound to port %d.\n", PORT_NUMBER);
+
+    // クライアントからの接続を待機
+    listen_for_connections(server_socket);
+    log_msg("Server is listening on port %d...\n----------\n", PORT_NUMBER);
+
+    // シグナルハンドラの設定
+    struct sigaction sa;
+    sa.sa_handler = signal_handler;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = 0; // SA_RESTARTを設定しない（システムコールを自動再開しない）
+    if (sigaction(SIGINT, &sa, NULL) == -1) {
+        handle_error("sigaction failed");
+    }
+
+    // リクエストの受信と処理
+    while (is_server_running) {
+        int client_socket = accept_connection(server_socket);
+        
+        if (client_socket < 0) continue;
+        
+        log_msg("Client connected.\n");
+
+        handle_client_request(client_socket);
+        log_msg("Client request handled.\n");
+
+        close_socket(client_socket);
+        log_msg("Client socket closed.\n----------\n");
+    }
+
+    // サーバソケットのクローズ
+    close_socket(server_socket);
+    log_msg("\r\nServer shutdown gracefully.\n");
+    return 0;
+}
\ No newline at end of file
diff --git a/utils.c b/utils.c
new file mode 100644
index 0000000..6889bd5
--- /dev/null
+++ b/utils.c
@@ -0,0 +1,35 @@
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include "utils.h"
+
+void handle_error(const char *msg) {
+    perror(msg);
+    exit(EXIT_FAILURE);
+}
+
+void log_msg(const char *format, ...) {
+    va_list args;
+    va_start(args, format);
+    vprintf(format, args);
+    va_end(args);
+}
+
+int initialize_socket(const char* ip_version) {
+    // ソケットの初期化 (IPv4: AF_INET, IPv6: AF_INET6)
+    int domain = (strcmp(ip_version, "IPv6") == 0) ? AF_INET6 : AF_INET;
+    int tcp_socket = socket(domain, SOCK_STREAM, 0);
+    if (tcp_socket < 0) handle_error("Socket creation failed");
+
+    return tcp_socket;
+}
+
+void close_socket(int socket_fd) {
+    // ソケットのクローズ
+    if (close(socket_fd) < 0) {
+        handle_error("Close failed");
+    }
+}
\ No newline at end of file
diff --git a/utils.h b/utils.h
new file mode 100644
index 0000000..cffb1ab
--- /dev/null
+++ b/utils.h
@@ -0,0 +1,9 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+void handle_error(const char *msg);
+void log_msg(const char *format, ...);
+int initialize_socket(const char *ip_version);
+void close_socket(int socket_fd);
+
+#endif // UTILS_H
\ No newline at end of file