PURPOSE: To provide high sensitivity for writing by use of a semiconductor laser oscillating in a visible to near infrared region, obtain a high signal intensity and ensure favorable stability of a thin film condition, by incorporating a specified coloring matter into a recording layer.

CONSTITUTION: A recording layer comprising a coloring matter of formula I is provided. In formula I, X is formula II or III, wherein each of R1WR4 is hydrogen, a substd. or unsubstd. alkyl or alkoxyl, a halogen, nitro, cyano, hydroxyl or a substd. or unsubstd. amino, each of R5 and R6 is hydrogen, a substd. or unsubstd. alkyl, aryl or cyclohexyl, R7, is a substd. or unsubstd. alkyl or alkoxyl or -NHCOR, R8 is a substd. or unsubstd. alkyl, alkoxyl or amino, each of R and R' is hydrogen, a substd. or unsubstd. alkyl or aryl, R9 is hydrogen, a halogen, substd. or unsubstd. alkyl, aryl or heteroaryl, and each of R10WR12 is hydrogen or an alkyl.