JPH0139917B

PURPOSE:To improve the moisture resistance of a photo-recording medium by lessening regenerative deterioration by forming a recording layer containing a combination of a color cation and a quencher anion on a base material. CONSTITUTION:A recording layer containing a combination of a color cation and a quencher anion is formed on a base material. The color cation used includes various kinds of color cations, of which those having high writing sensitivity and a high read-out S/N ratio are ones with hetero rings containing positively charged hetero atoms or ones with positively charged methine chains. When a recording light is irradiated in a pulse form under running or turning condition, the color is melted by the exthothermic reaction of the color in the recording layer and pits are formed. The regenerative deterioration by reading- out light can be greatly lessened and also the deterioration of characteristics during storage in light rooms can be prevented due to the improved light resistance.