Copper alloy hot-forged part and process for producing copper alloy hot-forged part

This copper alloy hot-forged part has an alloy composition which contains 0.21 to 0.44 mass% of Co, 0.06 to 0.13 mass% of P, 0.003 to 0.08 mass% of Sn and 0.00003 to 0.0030 mass% of O, with the balance consisting of Cu and unavoidable impurities, and in which the Co content, [Co] mass%, and the P content, [P] mass%, satisfy the relationship: 3.1 ≤ ([Co] - 0.005)/([P] - 0.006) ≤ 4.9. In the cross-sectional metal structure, the sum of the fraction of recrystallized-grain groups where the recrystallized grains have an average grain diameter of 0.050 to 0.50mm and the fraction of un-recrystallized grains is 80% or above.