An information recording medium of the present invention includes N information 
layers on a substrate (1), where N is an integer of 2 or more. Information is recorded / reproduced by irradiating each of the information 
layers (11, 12) with a 
laser beam (4). When the N information 
layers are referred to as a first 
information layer to an N-th 
information layer sequentially from the opposite side to a 
laser beam incident side, the L-th 
information layer included in the N information layers includes at least a 
recording layer (135) capable of undergoing a 
phase change through 
laser beam 
irradiation, a 
reflective layer (132), and a 
transmittance adjusting layer (131) in this order from the laser beam incident side, where L is an integer satisfying 2≦L≦N. The 
transmittance adjusting layer (131) contains Nb, 
oxygen (O), and at least one element M selected from Ti, Zr, Hf, Y, Cr, Zn, Ga, Co, Bi, In, Ta, and Ce. In the 
transmittance adjusting layer (131), the content of Nb is at least 2.9 atom %.