A blood collection tube holder comprising: a blood collection tube holder body having a hollow bottomed tubular shape; and a holding member that is internally fitted to an inner peripheral surface of the blood collection tube holder body and detachably holds a blood collection tube (3a, 3b, 3c) that is inserted into a hollow part of the blood collection tube holder body, wherein the blood collection tube holder body includes a needle base provided at a bottom part, a hollow needle tube supported by the needle base and protruding into the hollow part of the blood collection tube holder body, and an elastic sheath body covering the needle tube across an entire length of the needle tube, the holding member includes a fitting member that has a hollow tubular shape and is internally fitted to the inner peripheral surface of the blood collection tube holder body, and a plurality of press-contact members that protrude from the fitting member into the hollow part of the blood collection tube holder body and that swing toward the inner peripheral surface of the blood collection tube holder body and are pressed to contact an outer peripheral surface of the blood collection tube (3a, 3b, 3c) by elastic force of the press-contact members when the blood collection tube (3a, 3b, 3c) is inserted into the hollow part of the blood collection tube holder body, characterized in that the blood collection tube holder body includes a plurality of tongue-shaped protrusion pieces protruding into the hollow part of the blood collection tube holder body, and in that when the blood collection tube (3a, 3b, 3c) is inserted into the hollow part of the blood collection tube holder body and the press-contact members swing toward the inner peripheral surface of the blood collection tube holder body, the tongue-shaped protrusion pieces contact leading ends of the press-contact members, swing toward the inner peripheral surface of the blood collection tube holder body, and assist, with elastic force of the tongue-shaped protrusion pieces, the press-contact of the press-contact members with the outer peripheral surface of the blood collection tube (3a, 3b, 3c). a blood collection tube holder body having a hollow bottomed tubular shape; and a holding member that is internally fitted to an inner peripheral surface of the blood collection tube holder body and detachably holds a blood collection tube (3a, 3b, 3c) that is inserted into a hollow part of the blood collection tube holder body, wherein the blood collection tube holder body includes a needle base provided at a bottom part, a hollow needle tube supported by the needle base and protruding into the hollow part of the blood collection tube holder body, and an elastic sheath body covering the needle tube across an entire length of the needle tube, the holding member includes a fitting member that has a hollow tubular shape and is internally fitted to the inner peripheral surface of the blood collection tube holder body, and a plurality of press-contact members that protrude from the fitting member into the hollow part of the blood collection tube holder body and that swing toward the inner peripheral surface of the blood collection tube holder body and are pressed to contact an outer peripheral surface of the blood collection tube (3a, 3b, 3c) by elastic force of the press-contact members when the blood collection tube (3a, 3b, 3c) is inserted into the hollow part of the blood collection tube holder body, characterized in that the blood collection tube holder body includes a plurality of tongue-shaped protrusion pieces protruding into the hollow part of the blood collection tube holder body, and in that when the blood collection tube (3a, 3b, 3c) is inserted into the hollow part of the blood collection tube holder body and the press-contact members swing toward the inner peripheral surface of the blood collection tube holder body, the tongue-shaped protrusion pieces contact leading ends of the press-contact members, swing toward the inner peripheral surface of the blood collection tube holder body, and assist, with elastic force of the tongue-shaped protrusion pieces, the press-contact of the press-contact members with the outer peripheral surface of the blood collection tube (3a, 3b, 3c).