In an information recording medium in which storage capacity per recording layer has increased so much that the size of an SBM varies with those of spare areas, there is mutual dependence between a DDS and an SBM and it is difficult to retrieve disc management information as intended. In an information recording medium according to the present invention, if the largest space is allocated to an user data area, the number of blocks to store a space bitmap is Ni (where Ni≧2). But if the smallest space is allocated to the user data area, the number of blocks to use is smaller than Ni. In such an information recording medium, if the number of blocks to store the space bitmap of a recording layer is Mi (where 1≦Mi≦Ni) and if Mi is equal to or greater than two, the space bitmap is divided into the 1st through Mith space bitmaps, each of which has a size that is still equal to or smaller than one block even when combined with a DDS, and each space bitmap is stored in an associated one of Mi blocks in a disc management area.