A putter head includes a head main body having a depressed portion and a face insert disposed within the depressed portion so that the face insert is mounted in a face surface of the head main body. The face insert includes at least one low hardness portion and at least one high hardness portion. The face insert has a boundary face between the at least one low hardness portion and the at least one high hardness portion which is inclined relative to a back-to-forth direction of the putter head. The boundary face may decline toward the rear or may rise toward the rear. The face insert may comprise a plurality of the low hardness portions and a plurality of the high hardness portions so that the low and high hardness portions are arranged vertically in multiple layers. The sectional shapes taken perpendicularly to the back-to-forth direction of the high hardness portion and the low hardness portion may be substantially of a right triangle. The face insert may comprise a surface layer and groove portions on a front face thereof.