Planographic printing plate precursor

A planographic printing plate precursor comprising:

• a support;
• a hydrophilic layer comprising a hydrophilic polymer chemically bonded to a surface of the support, where the hydrophilic polymer has a positively-charged substituent and at least one reactive group selected from the group consisting of a reactive group capable of directly chemically bonding to a surface of the support and a reactive group capable of chemically bonding to a surface of the support via a crosslinked structure;
• and
• an image forming layer,
• wherein the hydrophilic layer and the image forming layer are provided in that order on the support,
• wherein the hydrophilic polymer includes a structural unit (i) and a structural unit (ii) of the following Formula (1):
• wherein Formula (1) represents a polymer having a silane coupling group represented by the structural unit (i) on an end of a polymer unit represented by the structural unit (ii);
• wherein in Formula (1):
• R1, R2, R3, and R4 each independently represents a hydrogen atom or a substituent having 1 to 30 carbon atoms;
• m represents 0, 1, or 2;
• L1 and L2 each independently represents a single bond or an organic linking group;
• and Y1 represents an ammonio group, a substituted ammonio group, a phosphonio group, or a substituted phosphonio group;
• and
• wherein the counter anion of the positively-charged substituent is SO42−, S2O32−, SO3−, a halogen ion, ClO4−, BF4−, PF6−, SbF6−, BiCl5−, AsF6−, SbCl6−, SnCl6−, R—SO3−, or R—COO−, wherein R is a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.