This invention provides a copper-base alloy casting with refined crystal grains, which comprises by mass Cu: 69 to 88%, Si: 2 to 5%, Zr: 0.0005 to 0.04%, and P: 0.01 to 0.25% and satisfies 60 = Cu - 3.5 Si - 3 P = 71, with the balance consisting of Zn and unavoidable impurities. The average grain size after melting and solidification is not more than 100 [mu]m. Regarding the phase structure, the percentage total area of a phase, phase, and phase is not less than 80%. At least one element selected from the group consisting of Mg: 0.001 to 0.2%, B: 0.003 to 0.1%, C: 0.0002 to 0.01%, Ti: 0.001to 0.2%, and rare earth element: 0.01 to 0.3% may be further contained.