The present invention relates to a device for supplying power to a surgical instrument for amputating a surgical site or stopping bleeding by using ultrasonic waves, comprising a control unit for controlling the intensity of current flowing into a vibrator, which is provided at the surgical instrument to control the intensity of ultrasonic waves oscillated at the surgical instrument, wherein the current control unit controls the intensity of current flowing into the vibrator such that weakening the intensity of current, flowing into the vibrator, for a predetermined time period can be periodically repeated.
