An energy control device for an ultrasonic treatment tool which includes an ultrasonic transducer and an end effector that performs a treatment using the ultrasonic vibration generated by the ultrasonic transducer comprises a first power supply configured to supply an electric power to the ultrasonic transducer, and a circuit. The circuit is configured to measure an output duration, monitor a characteristic parameter representing a situation of the treatment, set a time threshold value based on the characteristic parameter, and perform, when the output duration exceeds the time threshold value, at least one of: stopping or reducing the output of electric power from the first power supply to the ultrasonic transducer and notifying that the output duration has exceeded the time threshold value.
