A head 2 has three regions, i.e., an anterior region Z positioned on the facemost side, a posterior region K positioned on the backmost side, and a joint region R positioned between the anterior region Z and the posterior region K, which are provided to divide the putter head equally in the face-to-back direction. The anterior region Z has an anterior thick part Z1 having a thickness of equal to or greater than 20 mm. The joint region R has a thin part 16 having a thickness of equal to or less than 7 mm. The posterior region K has a posterior thick part K1 having a thickness of greater than 7 mm. The joint region R has a full-width part 23 formed by making the full width of this joint region to correspond to the thin part 16. Provided that the length of the head 2 in the face-to-back direction is A1, the length of the full-width part 23 in the face-to-back direction is equal to or greater than (A1/6).