A photoresist supply apparatus of semiconductor coating equipment fills a supply pipe with new photoresist when a used photoresist bottle is replaced. The photoresist supply apparatus includes first and second photoresist bottles, first and second gas supply pipes connected to the bottles, first and second solenoid valves disposed along the gas supply pipes, first and second purge start buttons, first and second photoresist supply pipes, first and second trap tanks to which the supply pipes are connected, a third photoresist supply pipe connected to the trap tanks, a nozzle connected to the third photoresist supply pipe, first and second level sensors disposed at an upper level of the trap tanks, third and fourth level sensors disposed at a lower level of the trap tank, first and second discharge pipes connected to the trap tanks, third and fourth solenoid valves disposed along the discharge pipes, first and second drain sensors associated with the discharge pipes, and a controller.