An object of the present invention is to provide a lithographic printing plate with a hydrophilic layer mainly made from resins which has a photosensitivity to the light in near infrared region, on which images can be printed directly with laser beam, requiring no development and wiping off operation, and immediately recovering from ink stains without any difficulties when an ink attaches to non-image areas on printing, and a photosensitive resin composition applied to the printing plate.A lithographic printing original plate having a photosensitive layer formed on a support is characterized in that the surface of the photosensitive layer has a phase-separation structure, and the recessed parts are formed on the surface of a photosensitive layer by the dissolution of one component of photosensitive layer constituting the phase-separation and the surface of the photosensitive layer is changed to have affinity for ink by irradiation with light.