To easily add a new operator or function, and to prevent the operation by a third person when the operator forgets a logout operation.

Concerning this control system, when the operator performs a log-in, an operator group to which that operator belongs is retrieved from a person-in-charge group table 14, a function group corresponding to that operator group is retrieved from a security table 15, a function corresponding to that function group is retrieved from a function group table 16, and the function corresponding to that operation is executed. Besides, an automatic log-out mode is provided for automatically performing log-in after the lapse of fixed time when the operator performs log-in.