Provided herein is a door opening and closing apparatus capable of reducing torque of a motor required for removing an adhesive force between a door and a housing. The door opening and closing apparatus includes a motor configured to output power for opening and closing a door, a power transmission apparatus configured to transmit the power of the motor to a hinge by rotation of a plurality of driving gears, and an auxiliary apparatus configured to generate an auxiliary force for moving the door at a closing position toward an opening position, where the auxiliary force is generated at the auxiliary apparatus by the power of the motor before the power of the motor is transmitted to the hinge through the power transmission apparatus.