Provided is a motor controller that controls a motor system including: a power converter, a smoothing capacitor, a three-phase AC motor, and a current sensor. The motor controller is provided with an electronic control unit. The electronic control unit specifies a target phase that is a phase of a second phase voltage command signal having a largest difference from a first phase voltage command signal having a signal level that is neither a maximum nor a minimum signal level, based on three phase voltage command signals generated from the detection value of the current sensor, and corrects the detection value of the current sensor, which detects the phase current of the target phase, such that a terminal voltage of the smoothing capacitor matches the desired voltage value.