A control device for a pole-number switching electric motor applied to a system including an electric motor capable of switching a number of poles, and an inverter electrically connected to stator windings of the electric motor; includes: a basic operation unit configured to operate the inverter to control a current amplitude which is magnitude of a current vector flowing in the stator winding, and a switching operation unit configured to operate the inverter to reduce the current amplitude before switching and increase the current amplitude after switching. The switching operation unit, the pole number switching period, operates the inverter so that a total value of the current amplitude before switching and the current amplitude after switching does not exceed a limiting current value.