To improve the life of a die, and to stabilize the quality of a forged part by forming a hard facing layer having at least either chromium nitride or chromium carbon nitride on a contact surface between the die and a metallic stock.

As a die for forging, the die which a hard facing layer containing at least either chromium nitride or chromium carbon nitride has been formed on the contact surface of a metallic stock, is used. First of all, after applying nitriding to an unprocessed die, at least one nitriding layer out of iron nitride, iron carbon nitride and the diffusion layer of nitrogen is formed on the surface of the die. This die is heated to 500 to 700°C and held in a processing agent containing glass and chrome whose main component is the chloride of alkali or an alkaline earth metal and whose main component is silicon dioxide, and the chrome is diffused in the nitriding layer formed on the die. Consequently, the hard facing layer having at least either chromium nitride or chromium carbon nitride is formed.