To provide a motor drive device and a recording medium conveyance apparatus, capable of preventing out-of-step due to insufficient torque and vibration, and generation of heat due to excessive torque.

This motor drive device includes a voltage detector (voltage detection circuit) 9 for detecting the voltage applied to a stepping motor (motor) 3 and a current control device (controller) 11 for switching the current, passing through the stepping motor 3 in response to the voltage detected, and is structured so that the output torque of the stepping motor 3 is constant.