The present invention relates to a method of molding a low-melting-point metal alloy which exhibits thixotropy properties in a solid-phase and liquid-phase coexisting temperature region. In this method, a temperature of a heating holding cylinder is increased to a liquidus temperature or higher at the start of a molding operation. Then a remaining material in the preceding molding remaining in the heating holding cylinder in a solid state is wholly melted. After that a temperature of the heating holding cylinder is lowered to a temperature in the solid-phase and a liquid-phase coexisting temperature region. At the same time a molding material is supplied and a provisional molding is carried out. After the temperature has reached the solid-phase and liquid-phase coexisting temperature region, a regular molding is started. By the present invention a problem of a remaining material in the heating holding cylinder, which becomes a trouble at the start of molding by injection, is solved.