Provided is a vehicle-mounted active vibration reducing device wherein vibrations in a plurality of directions are reduced by a single dynamic damper. Since an actuator is attached so as to be supported by an elastic member attached to a bracket, the actuator can be used as a mass of a dynamic damper. The moving directions of the actuator are the forward and rearward directions, and are different from the moving directions of the dynamic damper using the actuator as a mass, i.e., the upward and downward directions. Accordingly, vibrations can be controlled in the forward and rearward directions which correspond to the moving directions of the actuator as well as the upward and downward directions which correspond to the moving directions of the dynamic damper.