A treatment device for an endoscope includes: a needle pipe which has flexibility, is formed in an elongated shape, and includes a piercing section and a side hole that is provided in an outer circumferential surface of the piercing section and communicates with an inner cavity of the needle pipe at a distal end of the needle pipe a collection member housed in the inner cavity and including a cup section that opens toward a radial outer side of the needle pipe and an operating member connected to the collection member and inserted into the needle pipe so as to be advanceable and retractable. The cup section protrudes from the side hole when the operating member is displaced relative to the needle pipe.
