A hand tool for providing high twisting forces and low damage to a screw includes a handle having a driving end. The driving end has an inner hexagonal space. The driving end has three engaging portions and three flat portions respectively form in six edges of the inner hexagonal space. The three engaging portions and the three flat portions are alternatively disposed. The driving end has six recesses. Each recess is disposed between the engaging portion and the flat portion adjacent to the engaging portion. Each engaging portion has two cambered protrusions and a sharp protrusion disposed between the two cambered protrusions. An apex of the sharp protrusion and those of the two cambered protrusions are collinear.