To prevent the occurrence of unstable operation such as system runaway by monitoring data access outside a memory work area allocated by the request of application as well concerning a memory managing device for information equipment such as an electronic notebook for which plural application programs are managed by the basic software of an OS, etc., and the entire system is controlled.

In response to the request of an application 17 for each mode operation previously stored in a ROM 13, fixed data ('0000'-'1111') for memory destruction inspection are written at the end of a work area 14b allocated to an allocatable area 14a of a RAM 14 according to a memory managing program 16a in a basic software (OS) 16 previously stored in this ROM 13 and when any change in these fixed data is confirmed at the time of confirming the relevant fixed data with the allocation cancel processing of the work area 14b due to the application 17, alarm message data showing 'memory destruction error' are displayed on a display device 15.