1. A method for street search by using a street data storage capable of storing, as a street name, a street name string in one of a divisional manner that uses a divider in the street name string to divide the string for storage and a continuous manner that spares use of the divider in the string for storage, wherein the street search takes place when a search string for the street search is provided, the method comprising: searching the street data storage for the street name that includes the search string for the street search in the street name string; and displaying, on a display unit, a street search result list of searched streets by using a display string in an order that lists the display string having the search string contained therein on a top side of the street search result list, wherein the display string containing the search string is defined as a string portion in the street name string when the street name string is stored in the divisional manner in the street data storage, and wherein the display string containing the search string is defined as the street name string itself when the street name string is stored in the continuous manner in the street data storage.