To obtain a copper alloy for electric/electronic parts improved in mechanical strength and conductivity by specifying the compsn. composed of Zr, Sn, Zn and Cu and regulating the content of O2.

This copper alloy is the one in which Cu is added with, by weight 0.01 to 0.1% Zr, 0.5 to 2.0% Sn and 0.5 to 5% Zn and, if required, furthermore, with ≤0.5% of one or more kinds among Ag, Si, Cr, Co, Mn, Ni, P, Fe, Ti, B, Be and Al, and, moreover, the content of O2 is regulated to ≤30ppm, and the improvement of its mechanical strength and conductivity can be obtd.