1. An information management method to be executed by a computer, the information management method comprising: accepting a registration request including information in which latitude and longitude are included, and correspondence information corresponding to the position information; generating one character string by alternately arraying one character of the latitude and another one character of the longitude, each of the one character and the other one character is in a same digit regarding all of the digits of each of the latitude and the longitude, or some digits from the least significant digit of each of the latitude and the longitude; and storing the correspondence information in a storage unit in a manner correlated with the character string as a key.