A ultrasonic treatment apparatus includes a gradual decrease detecting section detecting a gradual decrease start point at which a ultrasonic impedance value starts to gradually decrease, and a peak judging section judging whether or not a held tentative peak value that is a ultrasonic impedance value at the gradual decrease start point is a target peak. The ultrasonic treatment apparatus includes an ultrasonic control section outputting a vibration generating electric power in a second ultrasonic output mode where incision performance provided by an ultrasonic vibration becomes smaller than that in a first ultrasonic output mode before a peak detection point, when at least a prescribed time passes from the peak detection point at which the target peak is detected.
