An energy supplier of an ultrasonic treatment system can output an electric power in a first output mode and a second output mode in which the electric power supplied to a drive force generation unit during a unit time is higher than in the first output mode. A controller maintains an output state of the electric power in the first output mode when a judgment section judges that a load on an ultrasonic probe is less than or equal to a threshold, and switches the output state of the electric power to the second output mode when the judgment section judges that the load is more than the first threshold.