PURPOSE: To obtain a heat-resisting copper alloy for firing molds which has excellent thermal conductivity, high-temp. hardness and oxidation resistance and is usable over a long period of time by specifying a compsn. consisting of Ni, Al, Si, Ti, Zr, Mg and Cu.

CONSTITUTION: This heat-resisting copper alloy having the excellent thermal conductivity, high-temp. hardness and oxidation resistance is obtd. by using the compsn. contg. 2 to 10wt.% Ni, 1.1 to 2.5% Al, 0.2 to 0.8% Si, 0.05 to 0.6% Zr and 0.01 to 0.8% Mg, further, contg. 0.1 to 1.0% ≥1 kinds among Fe, Co and Mn at need, and the balance Cu with inevitable impurities. Then, the firing molds produced with this copper alloy are capable of maintaining the performance excellent in productivity, soaking property, thermal deformation resistance, etc., over a long period of time.