A head 2 is hollow. The head 2 has a face 4, a crown 6 and a sole 8. A rib 20 is provided on the inner surface of the head. Preferably, the rib 20 has a toe side part 20t located on the inner surface of a side 10 of a toe side, a sole disposing part 20s located on the inner surface of the sole 8, and a heel side part 20h located on the side 10 of a heel side. Preferably, the toe side part 20t and the sole disposing part 20s are connected with each other. Preferably, the sole disposing part 20s and the heel side part 20h are connected with each other.