A golf club head having a striking face configured to impact a golf ball comprises the striking face comprising an effective striking area, the effective striking area having an expected COR value, defined by the following expression, not less than 0.810, Expected ⁢ ⁢ COR = ∑ i = 1 n ⁢ ∑ j = 1 m ⁢ p ij * c ij wherein pij is an impact probability at location or region (i, j) within the effective striking area, and cij is a COR value of the location or region (i, j).