An information processing device in which memory bands can be significantly cut. In the present device, an access determining/managing portion (105) determines whether or not write data meets access determination conditions when write-accessing a memory (104), and manages this determination result and access location data (an address in the memory (104)) during the write access as access determination results (107), and does not perform a write access if the write data does not meet the access determination conditions. On the other hand, the access determining/managing portion (105) references the access determination results (the access location data and determination result) when read-accessing the address, and if the access determination results meet the access determination conditions when read-accessing the address, the data determined by the access determining conditions is returned to the master, without read-accessing the memory (104).