PRINTING SYSTEM OF OFFSET ROTARY PRESS AND OFFSET ROTARY PRESS

There is provided a printing system of an offset rotary press in which an emulsification state of ink can be grasped at real time and make it appropriate on quickly so that a good printing quality can be maintained from the start to the end of printing which results in reduction of paper loss.The printing system of an offset rotary press 1 comprising a light source 32 that irradiates irradiation light 71 on a surface of a plate cylinder 6 of a printing unit 5, a camera 33 for shooting reflected light 72 of the irradiated irradiation light 71 and a control device 56 for bifurcating a shot image of the camera 33 into a high brightness region and a low brightness region of reflected light 72 and calculates an area ratio of the region of high brightness of the reflected light 72 with respect to the entire area of the shot image of the camera 33, wherein if the area ratio in the high brightness region of the reflected light 72 calculated by the control means 56 is high, the dampening water supply of the dampening water device 11 is controlled such that an appropriate emulsification state of ink is obtained.