Disclosed is a developing process on a press of a planographic printing plate material comprising a hydrophilic layer and an image formation layer, which is capable of being developed with water or capable of being developed on a press, the process comprising the steps of (a) supplying dampening water to the planographic printing plate material with a recorded image mounted on a plate cylinder of a press by bringing a dampening roller into contact with the planographic printing plate material while rotating the plate cylinder, and (b) then supplying ink to the planographic printing plate material by bringing an ink roller into contact with the planographic printing plate material to remove an image formation layer unnecessary for printing, wherein in the step (a), the supplied amount of the dampening water is varied.