A grasping treatment device includes a first electrode portion functioning as an electrode when a high-frequency current is transmitted thereto through a probe unit, and a second electrode portion functioning as an electrode when a high-frequency current is transmitted thereto through a sheath unit. The grasping treatment device includes an inter-electrode distance changing unit changing an inter-electrode distance so that a second distance between the electrode portions in a second treatment mode, in which the high-frequency current alone is transmitted to the two electrode portions, is smaller than a first distance between the electrode portions in a first treatment mode, in which at least an ultrasonic vibration is transmitted to a probe electric conducting portion.
