A plate making method of a lithographic printing plate precursor includes: exposing imagewise a lithographic printing plate precursor including a support and an image-forming layer and containing (A) a compound generating an acid with light or heat, (B) an aromatic hydrocarbon compound or heterocyclic compound substituted with a functional group containing a nitrogen atom and (C) an aromatic aldehyde protected with an acid-decomposable group; and removing an unexposed area of the image-forming layer of the lithographic printing plate precursor by supplying at least one of dampening water and ink on a cylinder of a printing machine.