To obtain an alloy for cast parts of the frame of spectacles, excellent in castability and capable of providing required strength, and cast parts produced by using this alloy.

The alloy for cast parts, e.g. of the frame 1 of spectacles has a composition consisting of, by weight, 20-42% zinc, 5-15% nickel, 3-10% manganese, 0.1-3% aluminum, and the balance copper with inevitable impurities. It is preferable that this alloy contains 0.5-3% tin. By using nickel silver as a base and adding aluminum and manganese, a new alloy for cast parts of the frame 1 of spectables, having age hardenability while maintaining the properties of nickel silver, can be obtained. By performing casting by a lost wax process and carrying out age hardening treatment, the parts having ≥220 Vickers hardness can be provided.