PURPOSE: To prevent the deterioration in characteristics of a light sensitive layer due to rubbing, by forming a conductive processing layer on the back surface of the original paper of a supporting body with a mixture of a specified pigment, a bonding agent, a conductive agent, and wax.

CONSTITUTION: The condutive processing layer 5, which is provided on the back surface of the original form 1 of the lithographic press, is constituted by the following materials: a mixture of 70W95wt.pts. of clay as the pigment and 5W 30wt.pts. of calcium carbonate or zinc oxide; a mixture comprising weak anion or Nonion emulsion resin as a binding agent; a material wherein 10W30wt% of cation type high molecular electrolyte with respect to the total resin quantity is comounded as a conductive agent; and a material wherein 5W40wt% of wax emulsin with respect to the total resin quantity is compounded as a water repelling agent. An under coating layer 2, a waterproof layer 3, and a light sensitive layer 4 are sequentially laminated on the surface. Presserving property is excellent, and the deterioration in light sensitivity due to the rubbing between the surface light sensitive layer and conductive processing layer on the back surface can be prevented.