A hybrid turbocharger (10) includes a first power conversion unit (12) that has a function by which direct-current power is converted into alternating-current power and is output to a generator motor (30), a smoothing capacitor (18) that is provided between direct-current buses, and a control unit (40) that controls the first power conversion unit (12) so as to cause actual generator motor speed to comply with an engine speed command of the generator motor (30) input from an upstream controller during a motoring operation of the generator motor (30). The control unit (40) changes the engine speed command to a value which is equal to or greater than the actual generator motor speed when the engine speed command of the generator motor (30) is less than the actual generator motor speed and a direct-current bus voltage is equal to or greater than a predetermined first threshold value during the motoring operation of the generator motor (30). Accordingly, the direct-current bus voltage can be prevented from increasing during the motoring operation of the generator motor.