To inform a system manager efficiently about the repetitive occurrence of a slight or a warning symptom.

A symptom generating state section 21 classifies an occurrence state of symptoms into (A) a symptom abnormality state (symptoms take place at a specified frequency or over), (B) symptom consecutive occurrence state (symptoms take place at a specified frequency or less), and (C) symptom non-occurrence state (no symptom takes place). A symptom occurrence state notice section 22 informs the system management about the transition of the states above depending on occurrence and restoration of bubbling symptoms and occurrence and restoration of continuing symptoms. Thus, the state of symptoms taking place repetitively can efficiently be informed.