A motor driving apparatus includes an amplifier receiving, from a detector, a sine wave shaped signal detected in response to rotation of a motor, and amplifying the signal with a set amplification factor, an A/D converter for performing digital conversion by sampling the signal amplified by the amplifier at a sampling timing in a predetermined cycle, an amplification factor setting part for changing setting of the amplification factor of the amplifier, and an amplification factor set timing command part for issuing a command with respect to a timing for changing the setting of the amplification factor by the amplification factor setting part. The amplification factor set timing command part issues the command with respect to the timing so that a waveform stabilizing period until distortion in a waveform of the signal occurring when the amplification factor setting part changes the setting is stabilized does not overlap with the sampling timing.