A treatment tool for an endoscope including: an insertion section inserted from a mouth ring provided at the base-end portion of a channel of the endoscope to the inside of the channel; an operation section provided at the base end of the insertion section; a rigid guide member having a tubular shape, externally fitted around the insertion section at the base end of the insertion section, and fixed to the operation section; and a fixing section that is externally fitted around the guide member, firmly attaches between the inner wall of the mouth ring or the channel and the guide member, and fixes the guide member to the inner wall of the mouth ring or the channel.