PURPOSE: To suppress the deterioration in the corrosion resistance of a carbon carrier and the falling off of a metal catalyst by heat-treating the carbon carrier deposited with the metal catalyst in the atmosphere of gaseous hydrogen or gaseous hydrogen diluted with an inert gas.

CONSTITUTION: A pulverized metal catalyst is deposited on the carbon powder carrier, the carbon carrier deposited with the metal catalyst is placed in the atmosphere of gaseous hydrogen or gaseous hydrogen diluted with an inert gas to remove oxygen. The product is then heat-treated at high temp. to produce a deposited metal catalyst. By such treatment, the oxygen molecule remaining between the particles of the carbon carrier and in the pores can be removed by replacement with a gas, the oxygen adsorbed on the metal catalyst can also be removed, and loss in weight due to oxidation of the carbon carrier can be prevented.