The present invention provides a CPU-containing LSI in which software stored in an external memory is incorporated partially into a RAM and thereby the capacity of the RAM to be used can be held down, and an optical disk device including the same. In the CPU-containing LSI, the RAM includes a software storage region where software read in from the external memory on a module-by-module basis is stored, and an entry table in which entries are stored, with the entries each containing at least information as to a location and a size of a module stored in the software storage region. The CPU refers to the entry table to decide the location where a module to be read in from the external memory to the software storage region is to be stored, according to an incorporation-location search program.