This aims to provide a washing machine inverter device (99) for controlling a permanent magnet motor (11) mounted in a washing machine. The permanent magnet motor (11) comprises a rotor magnet (98) including a first permanent magnet (96) and a second permanent magnet (97) a lower coercive force than that of the first permanent magnet (96). The inverter device (99) generates an exciting current tochange the magnetization quantity of the second permanent magnet (97). The inverter device (99) decreases the magnetic flux of the rotor magnet (98) in a dehydrating operation, and increases the magnetic flux of the rotor magnet (98) for the operation, in which the highest rotation number is set lower than that of the dehydrating operation. In case the magnetization quantity of the second permanent magnet (97) is to be changed while the rotation of the permanent magnet motor (11) is standing, the inverter device (99) switches the phase of the exciting current to change the magnetization quantity, in accordance with the rotation stop position of a rotor (92).