The purpose is to suppress ripple of voltage between terminals of smoothing condenser. Electric motor control apparatus is electric motor control apparatus that controls electric motor system having electrical power converter, smoothing condenser and three-phase AC electric motor, and has generating device that generates modulation signal by adding third harmonic signal to phase voltage command signal; controlling device that controls operation of electrical power converter by using modulation signal; and adjusting device that adjusts amplitude of third harmonic signal, adjusting device adjusts amplitude of third harmonic signal so that peak value of voltage between terminals of smoothing condenser in the case where amplitude of third harmonic signal is adjusted is smaller than peak value of voltage between terminals in the case where amplitude of third harmonic signal is not adjusted.