A motor controller includes: a notch filter arranged inside a control system; an oscillation frequency estimating section which estimates an oscillation frequency component in a motor; and a notch control section which controls a notch filter so as to change a notch frequency and a notch width. The notch control section changes a frequency between an oscillation frequency and a notch frequency set in a notch filter as a new notch frequency, while changing a notch width to a new notch width such that the notch width is larger after the change than before the change.