Plate-making method of lithographic printing plate precursor

A plate-making method of a lithographic printing plate precursor, which comprises:

• exposing a lithographic printing plate precursor comprising a support and a photosensitive layer by utilizing an inner drum exposure apparatus having mounted thereon a light source having an oscillation wavelength in a range from 360 to 450 nm;
• and then removing a photosensitive layer in an unexposed area by rubbing the plate surface with a rubbing member in a presence of a developer at a pH of 2 to 10 in an automatic processor equipped with a rubbing member,
• wherein the photosensitive layer comprises a photosensitive composition comprising:
• a sensitizing dye capable of absorbing light at 360 to 450 nm;
• a polymerization initiator;
• a polymerizable compound;
• and a hydrophobic binder polymer,
• wherein the inner drum exposure apparatus produces a light beam spot shape of a light beam emitted from the light source in which the light beam is divided into an ordinary ray and an extraordinary ray parallel to each other at an equivalent light quantity, and two beam spots of the ordinary ray and the extraordinary ray are adjacently arrayed in a sub-scanning direction so as to partially overlap with each other, and
• wherein the lithographic printing plate precursor is loaded on the inner drum exposure apparatus and then subjected to image recording by exposure with the light beam spot shape.