A vibration reducing device that reduces the vibration of a control object includes a digital controller. A vibration state detection device detects the vibration of the control object and generates an analog signal of the vibration of the control object. An input-side bandpass filter has a passband that is narrower than a frequency range from a Nyquist frequency to a sampling frequency of the digital controller, and that contains no frequencies that are an integer multiple of the Nyquist frequency of the digital controller. The input-side bandpass filter allows a part of the analog signal that falls within the passband from the analog signal generated by the vibration state detection device to pass. An A/D conversion device converts the analog signal that has passed through the input-side bandpass filter into a digital signal. A D/A conversion device converts a digital feedback control signal, determined by the digital controller on the basis of the digital signal converted by the A/D conversion device, into an analog feedback control signal. An actuator applies vibration to the control object on the basis of the analog feedback control signal converted by the D/A conversion device.