A method for forming a colored image with good visibility on a lithographic printing plate precursor by exposure to a laser light, particularly, a method for forming a colored image with good visibility on a lithographic printing plate precursor which is developable on a printing press, the method for forming a colored image comprising: exposing a lithographic printing plate precursor to a laser light; and heating or exposing the entire lithographic printing plate to form a colored image, wherein the lithographic printing precursor comprises a support and a photosensitive-thermosensitive layer capable of recording an image by exposure to an infrared laser, the photosensitive-thermosensitive layer containing an infrared absorbent and a discoloring material that undergoes color change upon exposure.