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.