To improve detection accuracy of presence/no presence of a master on a plate cylinder even when the master having a porous support formed thin is used.

A rear end sheet 21 having light reflectance different from that of the master is provided to the rear end detection place where the rear end part in the plate cylinder rotational direction of the master is wound, in a master winding part on the surface of a plate cylinder 1 around which a master 8 is wound. Reflected light from the rear end detection place is received by an optical sensor 18 to detect winding of the master around the plate cylinder. When it is detected that the master is not wound around the place cylinder, an already manufactured master is wound around the plate cylinder.