To inexpensively produce soft ferrite and a porcelain material on which the soft ferrite is supported by means of a single furnace, for example, a gas furnace that has been used in the conventional pottery industry or the like and can fire ceramics or the like in an far more inexpensive running cost in comparison with an electric furnace and/or by utilizing the waste materials containing metal oxides and unused resources.

A raw molded body is placed in a single furnace, fired in an oxidative firing atmosphere during the step wherein the temperature is raised over about 1,150°C, then held at about 1,150-1,350°C in a reductive atmosphere, and cooled down as they are tightly sealed. The raw molded product is a metal oxide mixture having the soft ferrite composition or a combination thereof with porcelain materials. The single furnace is a gas furnace. In the reduction firing atmosphere, the concentration of carbon monoxide is ≥1%.