A door regulation apparatus positions a door mounted in a freely rotatably state in a vehicle body at a reference position in a gap/step measuring process, makes a step of a preset portion of the door to zero, and includes: i) a frame installed outside of a vehicle body transfer line; ii) a moving member reciprocating in the frame through a driving unit; iii) a clamping unit installed in the moving member vacuum adsorbs a skin surface of the door; iv) a sensor installed in the clamping unit senses a vacuum pressure operating at the skin surface; v) a vision photographing unit installed in the moving member photographs a preset portion of the door; and iv) a control unit analyzes and processes a sensing signal from the sensor and vision data that acquires from the vision photographing unit to control the driving unit.