An injection molding machine has a first servo amplifier configured to operate with a first voltage, a second servo amplifier configured to operate with a second voltage, and a transformer which has a primary side terminal and a secondary side terminal and transforms voltages mutually in a predetermined voltage ratio. A main power supply is connected to a primary side terminal or a secondary side terminal of the transformer, depending on whether a voltage of the main power supply supplied to the injection molding machine is equal to the first voltage or the second voltage, respectively. The first or the second servo amplifier is connected to a terminal of the transformer on the side where the main power supply is not connected.