To provide a method of surface treatment which enables occurrence of initial peeling to be prevented and, in addition, molten metal flowability for aluminum molten metal to be improved.

At least any one of titanium, zirconium, niobium, vanadium, hafnium, tantalum, and tungsten is provided onto a carbon film 11 that coats a surface of a base material 10, and the carbon film 11 is heated up to 400°C or higher in an inert atmosphere to produce a coat film 12 on the base material 10. After producing the coat film 12, the coat film 12 is cooled down to 200°C or lower in the inert atmosphere. After the coat film 12 is cooled down, the coat film 12 is subjected to ultrasonic cleaning in oil.