An electric motor drive device for driving an electric motor capable of switching a wire connection state of a stator winding, the electric motor drive device comprising: a wire connection switching unit to switch the wire connection state of the stator winding; an inverter to generate electric power to be supplied to the electric motor ; a control device to control the wire connection switching unit and the inverter ; and an overcurrent protection circuit to prevent a current exceeding a predetermined value from continuously flowing through the electric motor , characterised in that the overcurrent protection circuit includes: a plurality of determination circuits each correlated one-to-one with any one of a plurality of possible wire connection states of the stator winding, the plurality of determination circuits being configured to determine whether a current flowing through the inverter has an abnormal value; a combining circuit to combine determination results in the plurality of determination circuits ; and an invalidation circuit to invalidate a determination process by one or more of the plurality of determination circuits , and cause the combining circuit to output a determination result by the determination circuit correlated with a selected wire connection state of the stator winding, and when the determination result output from the combining circuit indicates that the current flowing through the inverter has an abnormal value, the control device stops the inverter . a wire connection switching unit to switch the wire connection state of the stator winding; an inverter to generate electric power to be supplied to the electric motor ; a control device to control the wire connection switching unit and the inverter ; and an overcurrent protection circuit to prevent a current exceeding a predetermined value from continuously flowing through the electric motor , characterised in that the overcurrent protection circuit includes: a plurality of determination circuits each correlated one-to-one with any one of a plurality of possible wire connection states of the stator winding, the plurality of determination circuits being configured to determine whether a current flowing through the inverter has an abnormal value; a combining circuit to combine determination results in the plurality of determination circuits ; and an invalidation circuit to invalidate a determination process by one or more of the plurality of determination circuits , and cause the combining circuit to output a determination result by the determination circuit correlated with a selected wire connection state of the stator winding, and a plurality of determination circuits each correlated one-to-one with any one of a plurality of possible wire connection states of the stator winding, the plurality of determination circuits being configured to determine whether a current flowing through the inverter has an abnormal value; a combining circuit to combine determination results in the plurality of determination circuits ; and an invalidation circuit to invalidate a determination process by one or more of the plurality of determination circuits , and cause the combining circuit to output a determination result by the determination circuit correlated with a selected wire connection state of the stator winding, and when the determination result output from the combining circuit indicates that the current flowing through the inverter has an abnormal value, the control device stops the inverter . <EOS>