To provide not only an image of a river condition in an optional point but also a water level data or the like.

This river information management system is provided with a data collecting means 2 for collecting an amount of rainfall/the water level data from a measuring instrument installed preliminarily, and for obtaining a meteorological data from various services, a geographical information/predicted water level database 8 stored with geographical information concerned in a river basin of an observation objective river, an image/position acquiring means 3 for acquiring image information and positional information transmitted from a cellular phone 30 added with a GPS function and a camera function, a computing means 4 for finding a predicted water level in the point of the positional information, and an information providing means 5 for providing at least one of the image information and a predicted water level data to a terminal, in response to a request from the terminal.