Simplification of a device configuration and control is realized, which enables attraction and release by a magnet without using a battery. A magnet work machine includes a generator motor (8) driven by an engine (7); and an inverter (10) which controls a magnet (6) and the generator motor (8) such that the magnet (6) is energized by electric power from the generator motor (8) to attract metal scraps or the like, and during demagnetization for releasing metal scraps or the like, electric power applied to the magnet (6) is transmitted to the generator motor (8) as regenerative power so as to be consumed. The inverter (10) determines a torque of the generator motor (8) as a motor according to a voltage change of a main circuit based on a detected main circuit voltage so as to suppress the voltage change, and gives the torque as a command.