A grasping treatment device includes a probe including a first electrode portion in its distal portion, and a jaw configured to open or close relative to the first electrode portion and including a second electrode portion. The grasping treatment device includes a grasping force converting unit converting a grasping force so that a second grasping force between the distal portion of the probe and the jaw in a second treatment mode in which high-frequency current alone is transmitted to the first electrode portion and the second electrode portion is greater than a first grasping force between the distal portion of the probe and the jaw in a first treatment mode in which at least an ultrasonic vibration is transmitted to the distal portion of the probe.