A driving tool including a guide groove shaped as a long hole receives a driver bit such that a portion thereof excluding its support is projectable outside of the handle body. The base material has the outline shape of the supporter of the driver bit and is formed so that it might project to the inner side in the inside wall of the circumference wall by the side of the central part of the guide groove of the top plate of the cap. The locking piece is formed in the inner wall of the open end of the cap so that it can stop the rotation part which can prevent a plurality of driver bits from entering the guide groove of the cap.