To solve the problem that weather forecast or the like can be judged only roughly since it is the information that stays for each prefecture, and there are no alarm reporting systems for reporting danger at each point closely to such small area as municipalities, river basin, or the like.

An alarm automatic reporting system is composed for the users of a cellular phone 5 and a mobile terminal, those who wish to know any danger, and the like at a basin concerned, an upstream region, an upper stream, an outer basin concerned, or an area where danger is assumed. For example, when the details of an alarm trigger (alarm reference value) are set to either of telemeter water level, telemeter time rainfall, accumulation rainfall or radar rainfall (time, accumulation, rainfall region movement) and the like to start an alarm trigger, alarm information such as mails and alarm signals is automatically reported to the user of the cellular phone 5 and the mobile terminal to report the danger in flood or the like.