A golf putter head 1 includes a head body having a face surface, and a head rear portion affixed to a back side of the head body and having a greater specific gravity than that of the head body. Provided that S1 represents a cross-sectional area of the head body with respect to a cross-section taken at a boundary portion K between the head body and the head rear portion and along a plane parallel to the face surface, whereas S2 represents a cross-sectional area of the head rear portion with respect to a cross-section taken at the boundary portion K and along a plane parallel to the face surface, a value of (S2/S1) is 1.1 or more and 2.0 or less.