Abstract: Disclosed are a method for ultrasonic fatigue testing at high temperature and a testing device without needing preliminary Young's modulus measurement, and a method for ultrasonic fatigue testing at high temperature and a testing device capable of securing heat insulation for protecting a vibrator without water cooling of a horn, measuring end surface displacement of a test specimen in a noncontact manner, and solving problems of a noncontact temperature measurement of a test specimen and temperature control. Young's modulus is calculated by inverse calculation, a rod and a horn having heat resistance, heat insulation, and temperature symmetry of a test specimen are used, laser light is irradiated and received from an oblique direction to measure end surface displacement, and a noncontact temperature measurement of a test specimen by a black-body coating and a two-color radiation thermometer and temperature control by a high-frequency coil having a special shape are performed.