A screwdriver is provided herein, comprising a handle portion (11) and a shaft portion (12), with a distal end attached to said handle portion (11) and a proximal end attached to a tip portion (13) for driving a screw member with rotation transmitted from said handle portion (11). The tip portion of the screwdriver has a substantially rounded cross-section in an axial plane, and a substantially polygonal shaped cross-section in a radial plane with at least a first and a second diagonal, extending perpendicularly to two opposite sides of the polygonal, respectively, wherein said first diagonal is greater than said second diagonal. Also, a screw member, adapted for said screwdriver, is provided.