To eliminate use of a printing plate image area measuring device which reads a printing plate by direct scanning, by measuring image areas of original plate films from an image data and adding image areas of all original plate films to be printed on the printing plate based on a multiple face printing data.

A printing plate making system comprises a plurality of printing devices 1 for printing on multiple face of an unexposed printing plate P by using original plate films F, a film recording device 2 for recording an image on the unexposed films based on an image data so as to form the original films F, a conveyor 3 for conveying the printing plate P printed by the printing devices 1, a burn-off device 4 for receiving the conveyed printing plate P and burning off the periphery of the printing plate P, a developing device 5 for developing the printing plate P, a stocker 6 for stocking the developed printing plate P, and a control device 7 for controlling the system. At the control device 7, image areas of all original plate films F are added so as to obtain a total image area.