An automatic biopsy gun, comprising: - a box-shaped body, - a needle cantileverly extending from the box-shaped body in a longitudinal direction (X-X), wherein the needle in turn comprises a stylet provided with a collecting hollow to collect a tissue sample, and a cannula, wherein the stylet is slidingly housed in the cannula so that the collecting hollow can come out of the cannula and go back in it with a guillotine effect, - a first pushing member constrained to the cannula and movable in the box-shaped body in a longitudinal direction between a forward position of the first pushing member, at which the cannula is completely extended from the box-shaped body, and a rearward position of the first pushing member, at which the cannula is partially inserted in the box-shaped body, - a second pushing member constrained to the stylet and movable in the box-shaped body in the longitudinal direction between a forward position of the second pushing member, at which the stylet is completely extended from the box-shaped body, and a rearward position of the second pushing member, at which the stylet is partially inserted in the box-shaped body, - elastic countering means (21, 33) to counter the first pushing member and the second pushing member, and - driving means to drive the first pushing member and the second pushing member, operable by the user, wherein the first pushing member and the second pushing member are guided by respective inner guides (22, 32) that are inside the box-shaped body, wherein the inner guide of the first pushing member and the inner guide of the second pushing member are staggered in the longitudinal direction, characterized in that the first pushing member and the second pushing member are movable in their respective inner guides (22, 32) parallel to one another in the longitudinal direction. - a box-shaped body, - a needle cantileverly extending from the box-shaped body in a longitudinal direction (X-X), wherein the needle in turn comprises a stylet provided with a collecting hollow to collect a tissue sample, and a cannula, wherein the stylet is slidingly housed in the cannula so that the collecting hollow can come out of the cannula and go back in it with a guillotine effect, - a first pushing member constrained to the cannula and movable in the box-shaped body in a longitudinal direction between a forward position of the first pushing member, at which the cannula is completely extended from the box-shaped body, and a rearward position of the first pushing member, at which the cannula is partially inserted in the box-shaped body, - a second pushing member constrained to the stylet and movable in the box-shaped body in the longitudinal direction between a forward position of the second pushing member, at which the stylet is completely extended from the box-shaped body, and a rearward position of the second pushing member, at which the stylet is partially inserted in the box-shaped body, - elastic countering means (21, 33) to counter the first pushing member and the second pushing member, and - driving means to drive the first pushing member and the second pushing member, operable by the user, wherein the first pushing member and the second pushing member are guided by respective inner guides (22, 32) that are inside the box-shaped body, wherein the inner guide of the first pushing member and the inner guide of the second pushing member are staggered in the longitudinal direction, characterized in that the first pushing member and the second pushing member are movable in their respective inner guides (22, 32) parallel to one another in the longitudinal direction.