Abstract

A check memory stores the data to limit a range of terminal devices usable by operators and a range of items accessible by operators, such as files, data and application programs. When an operator operates a computer system, he enters his personal identification data to the computer system by a termainal device. A checker contained in the computer system checks if the operator specified by the entered personal identification data is authorized to use the terminal device, and if he is authorized to access the entered file. The check is performed based on the contents of the check memory. When he is authorized, the executed of the job is permitted. When he is not authorized, the execution of the job is prohibited. A personal data memory stores the data of his personnel administration and the data of his section in a company. When the section to which an operator has belonged is changed to another section, the personal data in the personal data memory is changed. In this case, a security level changing unit checks its change, and if necessary, changes the contents of the check memory, thereby to change the range of job to be executed by that operator.