A power converter is for a rotating electrical machine including first and second winding sets, each of which has coils corresponding to phases of the rotating electrical machine. In the power converter, a first inverter energizes the first winding set, a second inverter energizes the second winding set, a current sensor detects a phase current flowing through each coil, and a control section drives the first and second inverters respectively based on first and second voltage command signals. The first inverter and the first winding set form a first system. The second inverter and the second winding set form a second system. The control section calculates the first and second voltage command signals so that average voltages applied to the first and second winding sets can be different from each other. The failure detector detects whether a short-circuit occurs between the first and second systems based on each phase current.