1. An inspection system for paint coated film of steel bridge using image processing technique comprising: a photograph means that output photograph image information of a paint coated film of a steel bridge; a computer unit that displays a percentage of deteriorated area on an output unit and calculates a time for repainting and an optimum method for paint coating after diagnosing a deterioration type of a photograph file of photographed paint coated film photographed by the photograph means and separately detecting a rust part and a scale part by an image processing process; and a data base (DB) unit that stores the image information of a paint coated film of a steel bridge photographed according to a function control signal of the computer unit, and stores calculated information including a deteriorated image of a paint coated film processed by the image processing process and the time for repainting as well as manages various stored information processed by the inspection system for paint coated film.