A processor (10) manages, in an instruction management unit (103) and a data attribute management unit (105), secure attributes indicating whether instruction code and data stored in an instruction cache (102) and a data cache (104) of the processor (10) are confidential information. When the instruction code and the data are confidential information, the processor (10) also manages secure processing identification information for indicating in which secure process the confidential information is to be used. When the operating mode is switched from the secure mode to the normal mode, only the confidential information is disabled by a memory disabling unit (108). This prevents confidential information from being analyzed by the processor in the normal mode.