A dc motor driving apparatus comprising a full-wave rectifier bridge circuit for supplying dc power to a dc motor and a dc motor driving control circuit for controlling the turning on and off of thyristors forming the full-wave rectifier bridge circuit, further comprises a protecting control circuit operatively associated with the dc motor driving control circuit for preventing the occurrence of a short-circuit mode in the full-wave rectifier bridge circuit caused by a malfunction of the thyristors and ensuring highly efficient, quick responsive and stable control of the reversing, braking, stopping and other speed changing operations of the dc motor.