An apparatus for regenerating a diesel particular matter filter includes an outdoor temperature sensor for detecting an outdoor temperature, a water temperature sensor for detecting a cooling water temperature of an engine, an air heater for heating intake air of the engine, a relay temperature sensor for detecting a heater relay temperature, a controller for generating and outputting a signal for controlling a heater relay to activate or deactivate the air heater and a signal for controlling a cooling fan to be operated based on detection values input from the outdoor temperature sensor, the water temperature sensor and the relay temperature sensor, a heater relay configured to be turned on and off depending on the control signal output from the controller to operate or stop the air heater, and a cooling fan configured to be selectively operated depending on the control signal output from the controller and ventilate air for cooling the heater relay upon the operation.