A method for manufacturing a head 2 includes the steps of: (A) producing a plurality of head components Ph; (B) welding at least two of the head components Ph to each other while abutting the head components Ph on a guide core gc1; and (C) removing the guide core gc1. Preferably, the guide core gc1 is made of a water-soluble material. Preferably, at least one of the head components Ph is produced by a press process. Preferably, the guide core gc1 has a lack part Ms1. Preferably, existence of the lack part Ms1 avoids contact between a welding joint part wd1 and the guide core gc1 in the step B.