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 which the candidates are consecutive in each group but not consecutive between different groups; a lower level selection unit that selects one of the specified lower level candidate groups; a candidate display unit that displays, within the acquired current level candidate group, a candidate that is not in one of the specified lower level candidate groups; a candidate selection unit that selects the displayed candidate; and an output unit that outputs the selected candidate as a search result, wherein the current level acquisition unit acquires, as the current level candidate group, all of the candidates or the selected lower level candidate group.