Process for making lithographic printing plate

A process for making a lithographic printing plate, which comprises subjecting a lithographic printing material having at least a silver halide emulsion layer containing at least one of sensitizing dyes represented by the following formulae (I), (II) and (III):

• wherein Z1 represents a group of atoms necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring, Q1 represents O, S, NR11 or CO—NR12, and Q2 represents O, S or NR13, where R11, R12 and R13 may be the same or different from each other and each represents a hydrogen atom, an alkyl group, or an aryl group, and M1 represents a counter ion for neutralizing an electric charge of the molecule,
• wherein Z2 and Z3 each represents a group of atoms necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring, provided that both of Z2 and Z3 do not contain a sulfur atom simultaneously, R1 and R2 may be the same or different from each other and each represents an alkyl group, L1 represents a methyne group, and M2 represents a counter ion for neutralizing an electric charge of the molecule,
• wherein Z4 represents a group of atoms necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring, R3 and R4 may be the same or different from each other and each represents an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group or a cyano group, and M3 represents a counter ion for neutralizing an electric charge of the molecule,
• and a physical development nuclei layer on a support to scanning exposure by a scanning type exposure device on which a violet laser diode is mounted, and then subjecting to developing treatment,
• wherein the silver halide emulsion layer contains an organic desensitizing agent in which a sum of a positive electrode potential and a negative electrode potential of a polarograph is positive.