This research is to test the fatigue endurance of the material by using end bending of specimen. The testing material is S45C steel and forming to the standard size for testing. The specimens with a diameter of 8 mm required a different bending moment. It was found that the large bending moment affects the fatigue of the specimen. The specimen quickly damaged due to the high bending stress and there were a small number of load cycles. If the bending moment acting on the specimen was reduced to the bending stress decreased and the number of load cycles increasing. It was shown that the bending stress and the magnitude of the bending moment affected the fatigue of the material. Also the appearance of damage marks of the specimen will have a flaw around the fracture surface. Then the flaw will be enlarged until the specimen will be damaged by fracture.