1. A license plate recognition apparatus comprising: a detection unit configured to detect a plurality of quadrangles of license plate region candidates from input images; a character recognition unit configured to execute character recognition of a character region included in the detected license plate region candidates; and an output unit configured to select a license plate region candidate to be output from among the plurality of license plate region candidates detected by the detection unit based on a character recognition result and the information of the quadrangle of the respective license plate region candidates and output information relating to the selected license plate region candidate, wherein the output unit, in cases where positions of the license plate region candidates overlap, narrows the license plate region candidates to be selected by leaving the license plate region candidate whose angle of a quadrangle of the respective license plate region candidates is closer to a right angle, as the candidates.