An inspection system and method for paint coated film of steel bridge using image processing technique including a paint coated film image storing process that stores in a data base (DB) unit a paint coated film image information of a steel bridge photographed by the inspection system; a paint coated film information loading process that loads information stored in the DB unit through calling a file containing the paint coated film image information to be inspected; a scale and rust extracting process that displays a scale part and a rust part on an output unit after detecting the rust part and the scale part by use of the inspection system and storing a calculated percentage of deteriorated are in the DB unit; and a repainting information calculating process that calculates a time for repainting and provide an optimum method for paint coating by deteriorated image information of paint coated film.