A control apparatus includes, for at least two-phase signals detected from a resolver excited by a carrier signal having a carrier frequency fc, a first phase shifter that shifts a phase of a first phase signal of the resolver with a pole at a frequency f1 lower than the carrier frequency fc, a second phase shifter that shifts a phase of a second phase signal of the resolver with a pole at a frequency f2 higher than the carrier frequency fc, a signal generator that generates a correction signal for canceling out an error component of the carrier signal, and a synthesizer that synthesizes the phase-shifted first phase signal, the phase-shifted second signal, and the correction signal for canceling out the error component, in order to create a phase-modulated signal that is the carrier signal being modulated at a rotation angle of a rotor of the resolver.