A grasping treatment device includes a first electrode portion provided at least one of in a part between a jaw and a probe electric conducting portion in opening-and-closing directions of the jaw and in the probe electric conducting portion, and a second electrode portion provided at least one of in a part between the jaw and the first electrode portion in the opening-and-closing directions of the jaw and in a jaw electric conducting portion. 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 first electrode portion and second electrode portion, 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.