A golf club head comprises: a face portion having a front face forming a club face and a rear face facing a hollow; a sole portion extending backward from the face portion and having an outer surface forming an undersurface of the head and an inner surface facing the hollow, the sole portion provided with a tubular part whose hole forms a socket; and a weight member secured in the socket. The tubular part protrudes from the inner surface of the sole portion into the hollow. The sole portion is provided on the outer surface with at least one stiffening groove so that said at least one stiffening groove forms at least one stiffening rib on the, inner surface of the sole portion, and the stiffening groove is partially included in a vicinity zone which is defined as extending 10 mm from the socket.