A tissue collecting instrument which cuts and collects tissue includes a first member formed in a tubular shape and including an internal space and a side hole communicating with the internal space, a second member inserted into the internal space and configured to be movable relative to the first member, a first protruding portion provided on the first member and configured to protrude toward the inside of the side hole, and a second protruding portion provided on the second member and configured to protrude in a direction opposite to the first protruding portion, wherein the tissue is able to enter the internal space through the side hole when the first member and the second member are in a positional relationship in which the first protruding portion and the second protruding portion are spaced apart and facing each other.
