An endoscopic treatment device includes: an elongated needle pipe having flexibility a hollow shape section having an inner cavity formed in a distal end section of the needle pipe, and a side hole formed on an outer side surface of the needle pipe and communicating with the inner cavity a piercing section provided closer to a distal end side of the needle pipe than the hollow shape section and formed with a pointed tip a collection member including a cutting edge section having a pointed shape toward a radial outer direction of the needle pipe and protruding and retracting between a position where the cutting edge section is housed in the hollow shape section and a position where the cutting edge section protrudes from the side hole and an operating member advanceable and retractable relative to the needle pipe and including a distal end portion connected to the collection member.
