1. A motion vector detection apparatus comprising: a calculation unit configured to calculate a temporal distance between a frame to be coded and each of a plurality of reference candidate frames referred to by the frame to be coded; and a motion vector detection unit configured to search for a candidate motion vector between the frame to be coded and each of the plurality of reference candidate frames and detect a motion vector for the frame to be coded from the candidate motion vectors, wherein when the candidate motion vector is searched for between the frame to be coded and the reference candidate frame, an amount of the calculation performed by the motion vector detection unit is changed according to the temporal distance between the frame to be coded and the reference candidate frame calculated by the calculation unit, and a coding type of the reference candidate frame.