Screwdriver

The invention discloses a screwdriver. The screwdriver comprises a handle, a spiral groove and a screwdriver bar, wherein the spiral groove is formed in the handle and coaxial with the handle, the screwdriver bar is arranged in the spiral groove, and the rotating direction of the spiral groove is the left-hand direction. A mounting head is arranged at the end, located outside the handle, of the screwdriver bar. A tool bit is arranged on the mounting head and detachably connected with the mounting head. A plurality of groups of swivel bearings are arranged at the end, located in the handle, ofthe screwdriver bar. The adjacent swivel bearings are arranged on the two sides of the screwdriver bar, and the axial space between the adjacent swivel bearings is positive integer times the slot pitch of the spiral groove. Each swivel bearing comprises a positioning rod and a rolling ring, wherein the positioning rod is arranged on the lateral side of the screwdriver bar and is perpendicular to the screwdriver bar, and t