A hollow golf club head comprises a face portion having a front face defining a clubface and a rear face facing the hollow. The face portion is provided in the rear face with a central protrusion and a plurality of radial protrusions extending radially from the central protrusion towards the peripheral edge of the face portion. The radial protrusions include at least one variable-width radial protrusion having a variable width increasing towards the peripheral edge from the radially inside. Preferably, a variable-width radial protrusion extending towards the crown portion, and a variable-width radial protrusion extending towards the sole portion of the club head are included.