1. A location search device comprising: a character string storage portion that stores a plurality of search object character strings; a character input portion that includes a plurality of buttons; an input character display portion in which a character input through the character input portion is displayed, wherein when one of the plurality of buttons is repeatedly pressed or pressed continuously for a given time or longer, a plurality of characters assigned in advance to the one button is displayed in the input character display portion in a predetermined cyclic sequence; when one of the plurality of buttons is pressed, and then, another of the plurality of buttons is pressed, the character displayed in the input character display portion immediately prior to pressing of the other button is set as an input set character whose input has been set; and when the character is input through the character input portion following the input set character, a character string is input; an input candidate character string acquisition portion that acquires the search object character string that partially matches the character string input through the character input portion, as an input candidate character string, from the character string storage portion; and an input candidate character string display portion in which the input candidate character string acquired by the input candidate character string acquisition portion is assigned to a character string button through which the input candidate character string is input, and the input candidate character string assigned to the character string button is displayed, wherein the input candidate character string acquisition portion creates a plurality of compound character strings by combining the input set character string whose input has been set through the character input portion with the plurality of characters assigned in advance to the button that is pressed next, and the input candidate character string acquisition portion acquires the search object character strings that partially match the respective compound character strings, as the input candidate character strings, from the character string storage portion.