A hand tool includes a body provided with a mounting portion. The mounting portion includes six first recessed portions, six second recessed portions, and six locking faces. Each of the first recessed portions includes two grooves. Each of the second recessed portions includes two first arcuate faces and a second arcuate face. Each of the locking faces has a planar shape and is arranged between two of the second recessed portions. Each of the first recessed portions is arranged on one of the locking faces. The locking faces define an imaginary hexagonal portion having six sides coinciding with the locking faces respectively. The mounting portion of the body is mounted on a screw member. The screw member has six ribs received in the second recessed portions. Each of the ribs rests on one of the first arcuate faces.