To provide an injection molding apparatus which can hold a die to a prescribed high temp. and thus, can produce a molding having close structure in the case of injection-molding the metal, e.g. Mg alloy, and a die heating device assembled with this apparatus.

The metal injection molding apparatus 1 is provided with a raw material supplying device 5 for holding the Mg alloy, an injection device 9, a die device 11 containing the die and a die fastening device and the die heating device containing a high frequency induction heater 25 inserting/taking off through a gap between the dies at the time of opening the dies. The die heating device is provided with the high frequency induction heater 25, a control device 31 containing a high frequency generator and a flexible cable 29 for electrically connecting the high frequency induction heater with the control device. Further, a robot R for inserting/taking off the high frequency induction heater through the gap between the dies at the time of opening the dies is provided.