Patent ID: 7371504

Claim:
A lithographic printing plate precursor capable of forming an image upon irradiation with an infrared laser comprising in the order recited a support, a first layer containing as the main component an alkali-soluble resin and a second layer containing (a) as the main component, an alkali-soluble resin that is different from the alkali-soluble resin contained as the main component in the first layer and (b) a mixture comprising at least one kind of cyanine dye infrared absorbing agent having an absorption maximum wavelength of not shorter than 825 nm and at least one kind of cyanine dye infrared absorbing agent having an absorption maximum wavelength of shorter than 825 nm, wherein the alkali-soluble resin contained in the second layer is an alkali-soluble resin having a phenol group or an alkali-soluble resin having a sulfonamido group, and the difference of the absorption maximum wavelengths of the two kinds of cyanine dye infrared absorbing agents is not less than 15 nm and not more than 50 nm.