1. A search device, comprising: an input unit that inputs characters; a selection unit that selects candidates that correspond to the characters that are input by the input unit; a current level acquisition unit that acquires from the selected candidates, as a current level candidate group, a candidate group in which the candidates are consecutive in a specified display order; a lower level specification unit that specifies as lower level candidate groups, from the acquired current level candidate group, a plurality of sub-candidate groups of the candidates; a candidate display unit that displays in a specified display order corresponding to the candidates: a candidate that is not in the sub-candidate groups of the specified lower level candidate groups; and names of specified lower candidate groups, but does not display the individual candidates within the sub-candidate groups of the specified lower level candidate groups; a candidate selection unit that selects the displayed candidate; an output unit that outputs the selected candidate as a search result; and a lower level selection unit configured to receive a user selection of one of the lower level candidate groups, wherein the lower level specification unit specifies, as the lower level candidate groups, from the acquired current level candidate group, (1) a candidate group including all of the candidates of the current level candidate group consecutively from a first candidate of the current level candidate group to a median candidate of the current level candidate group not including the first candidate and the median candidate and (2) a candidate group including all of the candidates of the current level candidate group consecutively from the median candidate to a last candidate of the current level candidate group not including the median candidate and the last candidate, when the lower level selection unit receives a selection of one of the lower level candidate groups, the current level acquisition unit acquires, as the current level candidate group, all of the sub-candidate group of the user selected lower level candidate group, and the candidate display unit displays at least three candidates: the first candidate, the last candidate, and the median candidate in the acquired current level candidate group.