A system which comprises a message data base for storing help messages, a history buffer for storing the past statuses of an interactive processing system, an inference engine for determining a help message to be outputted, and a rule data base for storing the rules for determining a help message by said inference engine, determines an output help message on the basis of at least the past status history using said inference engine, furthermore outputs a help message by a user's command, selects a message data base to be used by the system at that time from a plurality of message data bases, or selects a rule data base to be used by the system at that time from a plurality of said rule data bases