PURPOSE: To easily melt even metal or the like having high hardness by reducing the m.p. of the metal or the like.

CONSTITUTION: A metal or the like is heated in an atmosphere under 250 to 2000 atmospheric pressure in a furnace filled with water vapor, by which the m.p. of the metal or the like reduces. For example, the inside of a stainless steel 3 as the material to be melted is filled with water vapor 1. At the same time, the stainless sheet 3 is housed in a treating furnace 2 pressurized to 2000 atomospheric pressure, is heated in the above atmosphere by a heater 4 and is melted at 800°C. This is the application of a principle that metal 15 converted into a saturated soln. by hot water (at 374°C under 221 atmospheric pressure).