Treatment tool for an endoscope

The treatment tool for an endoscope has an operation portion including an operation portion body and a slider. The operation portion body has a proximal end portion provided with a ring-like finger engaging portion, and a grip portion is formed to be adjacent to the finger engaging portion. The slider has a pair of flanges for engaging a finger and a finger rest extending from the flange adjacent the rear end portion. An operator can insert his or her thumb of one hand into the ring-like finger engaging portion, and engages another finger of the same hand between the pair of flanges of the slider. The operation portion body and the slider can be relatively moved thereby. Otherwise, the operator can also relatively move the operation portion body and the slider by gripping the grip portion of the operation portion body on his or her palm of one hand and by engaging the thumb of the same hand on the finger rest of the slider shaped like a hood.