To provide a negative type photosensitive planographic printing plate of which the non-imaging section can be removed with a chemical-free processing agent with no alkali agent added thereto, further of which the lipophilicity of the imaging section of the printing plate after development is excellent, and of which the ink receptivity in printing is excellent, in the planographic printing plate having at least a hydrophilic layer, a photosensitive layer, and an over layer in this order on a plastic film substrate.

In the planographic printing plate including at least the hydrophilic layer, the photosensitive layer having a photosensitive polymer with an ionic hydrophilic group, and further the over layer in this order on the plastic film substrate, the over layer includes a water-soluble polymer having a unit with a charge reverse to that of the photosensitive polymer.

COPYRIGHT: (C)2011,JPO&INPIT