An electric motor control device (300; 500) including a speed detector configured to detect a rotation speed of an electric motor or a speed of a load and a feedback control system configured to perform feedback control based on an output of the speed detector , the electric motor control device being configured to change a control bandwidth of the feedback control system, the electric motor control device (300; 500) comprising: a first notch filter (302; 502a) arranged in the feedback control system, the first notch filter (302; 502a) having a first notch frequency which is changeable, the first notch frequency being a center frequency; a first notch control section (304; 504a) which changes the first notch frequency to remove an oscillation component attributable to mechanical resonance related to the electric motor ; and a control coefficient setting section (305; 505) which changes the control bandwidth , wherein the feedback control system includes a feedback control section configured to generate a torque command based on a speed command, an output of the speed detector , and the control bandwidth set by the control coefficient setting section (305; 505), and supplies the torque command to the first notch filter (302; 502a), characterized in that , when the control coefficient setting section (305; 505) determines, based on the first notch frequency set by the first notch control section (304; 504a) and a currently set value of a control coefficient of the feedback control section , that a ratio of the first notch frequency and the control bandwidth is a predetermined value or higher or that the first notch frequency overlaps the control bandwidth, the control coefficient setting section (305; 505) decreases the control bandwidth of the feedback control system to stabilize the feedback control system. a first notch filter (302; 502a) arranged in the feedback control system, the first notch filter (302; 502a) having a first notch frequency which is changeable, the first notch frequency being a center frequency; a first notch control section (304; 504a) which changes the first notch frequency to remove an oscillation component attributable to mechanical resonance related to the electric motor ; and a control coefficient setting section (305; 505) which changes the control bandwidth , wherein the feedback control system includes a feedback control section configured to generate a torque command based on a speed command, an output of the speed detector , and the control bandwidth set by the control coefficient setting section (305; 505), and supplies the torque command to the first notch filter (302; 502a), characterized in that , when the control coefficient setting section (305; 505) determines, based on the first notch frequency set by the first notch control section (304; 504a) and a currently set value of a control coefficient of the feedback control section , that a ratio of the first notch frequency and the control bandwidth is a predetermined value or higher or that the first notch frequency overlaps the control bandwidth, the control coefficient setting section (305; 505) decreases the control bandwidth of the feedback control system to stabilize the feedback control system. <EOS>