diff --git a/README b/README
new file mode 100644
index 0000000..b6f92cc
--- /dev/null
+++ b/README
@@ -0,0 +1,3 @@
+CPUのサイクル数を取得する関数
+
+C言語で記述
diff --git a/cycle_counter.c b/cycle_counter.c
new file mode 100644
index 0000000..585609f
--- /dev/null
+++ b/cycle_counter.c
@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+typedef unsigned int uint32_t;
+typedef unsigned long int uint64_t;
+
+// x86_64
+static inline uint64_t cycle_counter(void) {
+    uint32_t eax, edx;
+    __asm__ __volatile__("rdtscp" : "=a"(eax), "=d"(edx)::"%ecx");
+    return (((uint64_t) edx) << 32) | eax;
+}
+
+int main()
+{
+	int tmp = 0;
+	uint64_t start, end;
+	int i = 0;
+
+	for (i = 0; i < 10; i++) {
+		start = cycle_counter();
+		tmp = 1 + 1;
+		end =cycle_counter();
+
+		printf("%ld\n", end - start);
+	}
+}