Patent ID: 8414710

Claim:
A surface treatment method for removing a passive film on a surface of a metal material, said surface treatment method comprising: raising the temperature of said metal material to a temperature at which the surface treatment is performed in a place in which amino resin is present, and during the raising of the temperature, removing the passive film by C, N and H which are liberated from the amino resin, wherein said surface of said metal material is modified by forming a hardened layer or a compound layer on said surface of said metal material subsequently to removing the passive film, performing a nitriding treatment, which comprises a combination of ammonia gas and an endothermic gas (RX gas), or a carburizing treatment after the removing of the passive film, wherein the performing of the nitriding treatment comprises applying the combination of the ammonia gas and the RX gas at a first predetermined temperature for a first predetermined period of time, and the performing of the carburizing treatment comprises applying a carburizing gas at a second predetermined temperature for a second predetermined period of time.