A rotating machine drive system, comprising a rotating machine having a plurality of windings, an inverter device for operating said rotating machine at variable speed, and a winding switching device for switching connections of the plurality of windings, said winding switching device having winding terminals (U1, U2, U3, U4), a semi-moving element having a short-circuit part facing said winding terminals (U1, U2, U3, U4) and also having a sliding part provided with first protrusions on the surface opposite from the surface having said short-circuit part, and a moving element facing the sliding part of said semi-moving element and having a sliding part provided with second protrusions on the surface facing the sliding part of said semi-moving element, said moving element being made to slide relative to said semi-moving element so as to change the connection between said winding terminals (U1, U2, U3, U4) and said short-circuit part and switch the connections of the plurality of windings by bringing the winding terminals (U1, U2, U3, U4) and the short-circuit part in mechanical contact or no contact dependent on the progress of sliding, wherein the inverter device comprises an inverter circuit for converting direct-current power, which is output from a direct-current power source, to alternating-current power and outputting the alternating-current power to the rotating machine through the winding switching device, wherein said short-circuit part comprises at least two cylindrical conductors, and a cylindrical non-conductive member is disposed between the cylindrical conductors adjacent to each other. a rotating machine having a plurality of windings, an inverter device for operating said rotating machine at variable speed, and a winding switching device for switching connections of the plurality of windings, said winding switching device having winding terminals (U1, U2, U3, U4), a semi-moving element having a short-circuit part facing said winding terminals (U1, U2, U3, U4) and also having a sliding part provided with first protrusions on the surface opposite from the surface having said short-circuit part, and a moving element facing the sliding part of said semi-moving element and having a sliding part provided with second protrusions on the surface facing the sliding part of said semi-moving element, said moving element being made to slide relative to said semi-moving element so as to change the connection between said winding terminals (U1, U2, U3, U4) and said short-circuit part and switch the connections of the plurality of windings by bringing the winding terminals (U1, U2, U3, U4) and the short-circuit part in mechanical contact or no contact dependent on the progress of sliding, wherein the inverter device comprises an inverter circuit for converting direct-current power, which is output from a direct-current power source, to alternating-current power and outputting the alternating-current power to the rotating machine through the winding switching device, wherein said short-circuit part comprises at least two cylindrical conductors, and a cylindrical non-conductive member is disposed between the cylindrical conductors adjacent to each other.