A remote diagnostic system for semiconductor manufacturing equipment which diagnoses user's semiconductor manufacturing equipment connected to a piece of diagnostic equipment which is provided by a third party through a communication network. The diagnostic equipment having at least one diagnostic program which diagnoses said semiconductor manufacturing equipment and a control section which starts the diagnostic program when accessed by a specific user terminal which has been given an access right, and the terminal sends data which is requested by the diagnostic equipment for diagnosis and receives a result of diagnosis from the diagnostic equipment.