A grasping treatment device includes a jaw attached to a distal portion of a sheath rotatably around a rotation axis perpendicular to a longitudinal axis, and configured to open/close relative to a distal portion of a probe in open/close directions perpendicular to the longitudinal axis and perpendicular to the rotation axis, and a support member provided between the probe and the sheath, and configured to prevent contact between the probe and the sheath. The support member includes a most-distal support member located on the most distal direction side, a position of the most-distal support member coinciding with the rotation axis of the jaw in directions parallel to the longitudinal axis.
