Information recording medium and reproduction device

An information recording medium comprising:

• a first region in which type identification information that identifies a type of the information recording medium is recorded by recesses and/or protrusions which are defined by a given modulation method and whose lengths are longer than a length of an optical system resolution limit of a playback device;
• a second region in which content data is recorded by recesses and/or protrusions which are defined by the given modulation method and which include a recess and/or a protrusion whose length is shorter than the length of the optical system resolution limit;
• and
• a blank region between the first region and the second region, wherein
• the first region includes first address information recorded therein in a first address data format,
• the second region includes second address information recorded therein in a second address data format that differs from the first address data format,
• the blank region (i) includes a portion in which the first address data format is switched to the second address data format and (ii) includes address information and no significant information other than the address information,
• the first region includes first error correction encoding data and the second region includes second error correction encoding data, and
• error correction encoding of third error correction encoding data in a region on an outer side of the blank region is identical to error correction encoding in the second region.