In a distal end portion of a flexible sheath 3 which is inserted integrally with an ultrasound transducer array 20, cell collecting hole portions 10 each including a through-hole which allows a distal end portion outer periphery and an internal space of the flexible sheath 3 to communicate with each other is provided, an edge 11 for specimen cutting is formed at an opening portion of an outer circumferential side of each of the cell collecting hole portions 10, and after the flexible sheath 3 is caused to reach a lesion part 41 or the like of a subject, specimen collection is performed without additionally inserting a biological forceps or the like into the flexible sheath 3, whereby a specimen 42 of a target site such as the lesion part 41 is reliably collected without unnecessarily increasing the number of times of insertion and extraction of an instrument into and from a body, and the burden on an examinee is reduced.
