A lithographic printing plate original plate capable of producing a large number of good printed sheets with a practical amount of energy while exhibiting excellent developing performance and printingwear resistance in a printing press and reducing contamination by wetting water, and a lithographic printing method. The lithographic printing plate original plate having an image recording layer ona support is characterized in that at least a part of unexposed portion of the image recording layer does not dissolve into the print ink and/or the wetting water but is removed as a film in a step ofdeveloping the original plate by supplying the print ink and/or the wetting water after it is set in a printing press and exposed imagewise or after it is exposed imagewise and set in a printing press. A lithographic printing method employing that original plate is also provided.