PURPOSE: To improve the strength, solderability, stress relaxing properties, corrosion resistance and stress corrosion cracking resistance by mixing a Cu-Zn alloy with a specified amt. of Si or furthermore with Sn and Ni.

CONSTITUTION: The compsn. of a copper alloy for electronic parts is constituted of, by weight, 5 to 25% is Zn, 0.01 to 3% Si and the balance Cu with inevitable impurities. If required, this alloy is furthermore mixed with 0.05 to 3% Ni and moreover incorporated with 0.001 to 2% of one or ≥ two kinds among P, Al, Fe, Pb, As, Sb, B, Co, Cr, Mn, Te, In, Zr, Hf, Be, Mg, Ag, Cd and Ge. The grain size of this copper alloy is preferably regulated to ≤15μm. By this compsn., stress corrosion cracking resistance which is a defect of the conventional brass can be improved.