Abstract: A weight adjustable golf club head is provided. The club head has a trough at a lower part of the club head's back and a weight positioned inside the trough. The trough is arranged to follow the curvature of the club head's bottom. The trough has a tapered mouth along the surface of the club head and a base. There is an insertion hole at a position along the trough. The weight could be inserted into the trough through the insertion hole, and then slid along the trough. The weight contains a seat, a bolt, and a loading ring. The seat has a locking rim and the positioning rim which are inside the trough's base and mouth respectively when the weight is slid into the trough. The seat's body and the locking rim have a number of breaks so that the locking rim could be stretched. When the bolt is screwed into or out of the seat, the locking rim would be stretched or retracted, so that the weight could be locked or un-locked in the trough.