An image recording medium is disclosed which comprising: an acid generating agent capable of generating an acid by the action of heat or an acid, which is represented by the following formula (1); and a compound of causing variation in the absorption region of from 360 to 900 nm by the intramolecular or intermolecular reaction triggered by the action of an acid:W.sup.1 OP (1)wherein W.sup.1 represents a residue of an acid represented by W.sup.1 OH, and P represents an acid-sensitive substituent capable of splitting off at a temperature of 150.degree. C. or less due to catalysis by W.sup.1 OH.