A golf club head comprises a face portion whose front face forms a clubface having a clubface roll of a radius R, and the clubface is provided with a plurality of parallel grooves extending straight at an angle of not more than 10 degrees with respect to the toe-and-heel direction of the head so as to form at least one lateral zone between the parallel grooves, wherein the above-mentioned at least one lateral zone is provided with a convex curve of a radius (r) smaller than the radius R of the clubface roll.
1. A golf club head comprising a face portion whose front face forms a clubface having a clubface roll of a radius R,
the clubface provided with a plurality of parallel grooves extending straight at an angle of not more than 10 degrees with respect to a toe-and-heel direction of the head so as to form at least one lateral zone between said parallel grooves, wherein
said at least one lateral zone is provided with a convex curve of a radius (r) smaller than the radius R of the clubface roll.
2. The golf club head according to claim 1 , wherein said at least one lateral zone includes one lateral zone on which a sweet spot of the head is positioned.
3. The golf club head according to claim 1 , wherein a sweet spot of the head is positioned within a width of one of the grooves, and said at least one lateral zone includes two lateral zones one on each side of said one of the parallel grooves.
4. The golf club head according to claim 1 , wherein a ratio (r/R) of said radius (r) and radius R is in a range of from 0.30 to 0.80.
5. The golf club head according to claim 1 , wherein said at least one lateral zone is a plurality of lateral zones existing between a position 10 mm downward of an upper edge of the clubface and a position 10 mm upward of a lower edge of the clubface in a vertical cross section including the sweet spot and the center of gravity of the head.
6. The golf club head according to claim 1 , wherein the convex curve is provided in a region extending toward a toe and a heel of the head by at least 10 mm in the toe-and-heel direction from a sweet spot.