A golf club head comprises a part made of a martensitic iron alloy which has: a nickel (Ni) content of from 9.0 to 12.0 weight %; a chromium (Cr) content of from 11.0 to 12.5 weight %; a titanium (Ti) content of from 1.5 to 1.8 weight %; a molybdenum (Mo) content of from 0.75 to 1.2 weight %; a carbon (C) content of not more than 0.05 weight %; a phosphorus (P) content of not more than 0.015 weight %; a silicon (Si) content of not more than 0.25 weight %; a magnesium (Mg) content of not more than 0.25 weight %; and a sulfur (S) content of not more than 0.01 weight %.