A tissue sampling device includes a flexible sheath 34 a needle tube 35 which is inserted into the sheath 34 so as to advance and retreat and with which biological tissue is punctured and an operating unit which is provided on a proximal side of the sheath 34 and is used for operating the advancing and retreating of the needle tube 35. This needle tube 35 has a distal portion provided with a slit 50 extending toward the proximal side from a distal opening 35c, and when the distal portion is in a state of protruding from a distal end of the sheath 34, at least a part of the distal portion is positioned further on the radially outside than the inner surface of the sheath when viewed from an axial direction of the needle tube 35.
