An object of the present invention is to provide a treatment instrument for sample collection, the treatment instrument enabling reliable performance of a procedure to collect a sample of, e.g., a lesion existing around a small lumen such as a bronchial periphery, and therefore, the treatment instrument includes a rod-like insertion portion 10 that can be inserted into a subject, and at least one sample collection portion 11 arranged on a side face of the insertion portion, the sample collection portion includes a link portion 11a supported on the insertion portion in such a manner that an end of the link portion serves as a rotation axis and the other end is pivotable relative to the rotation axis, and an advancing/retracting portion 11b connected to the other end of the link portion, the advancing/retracting portion advancing/retracting in an axial direction of the insertion portion, whereby the other end of the link portion pivots relative to the rotation axis, and when the advancing/retracting portion is located on a most proximal end side, the advancing/retracting portion and the link portion are connected in the axial direction and thereby become parallel to the insertion portion, when the advancing/retracting portion is located on a most distal end side, a part of the advancing/retracting portion and the link portion overlap and thereby become parallel to the insertion portion, and when the advancing/retracting portion is located between a proximal end portion side and a distal end portion side, the link portion is pushed out in a direction crossing the axial direction of the insertion portion by the advancing/retracting portion and thereby projects from the insertion portion.
