An information recording medium having a recording portion (3) where information is recorded/reproduced when a recording/reproducing light is applied. The recording portion (3) contains a first phosphor which absorbs a first light of wavelength λ1/n where λ1 is the wavelength of the recording light and emits a second light of wavelength longer than that of the first light and a photosensitive material of photon mode which absorbs the second light and its optical constant varies. The n-photon absorption sensitivity to the recording light for the first phosphor is larger than the n-photon absorption sensitivity to the recording light for the photosensitive material where n is two or more integer.