To provide a drive system for driving a plurality of permanent magnet built in type synchronous motors by one inverter which has higher starting characteristics than that a prior art has without lowering efficiency at synchronization or a power factor.

The drive system for the permanent magnet built in type synchronous motor includes a permanent magnet for constituting a pole on a rotor core and a squirrel cage secondary conductor. The drive system includes a winding switching unit 14 having a switch 12 for opening and closing the permanent magnet built in type synchronous motor 10 to the inverter 9 and a winding switching unit 11 for switching the winding of an armature winding to star connection or delta connection in response to the state of the opening or closing of the switch 12 according to a signal from an external unit between the synchronous motor 10 and the inverter 9. Further, a unit group in which a plurality of the winding switching units 14 are disposed in parallel by connecting the synchronous motor 10 is connected to the output terminal of a single inverter 9.