To accurately detect a motion vector of a subject with a minimized operation frequency by correcting an initial displacement vector based on overall motion characteristics of an extracted screen.

Motion vectors of a plurality of blocks located in the vicinity of a detecting object block in a current field are read from a vector memory 4 as a first candidate vector group, and a logic motion vector arithmetic part 3 determines, based on a camera parameter including the direction of a camera in photographing, coordinate changes on the screen as second candidate vectors with respect to each detecting object block or with respect to a predetermined specified block. An initial displacement vector part 5 selects a motion vector with a value most suitable to the motion of the detecting object block of the current field as an initial displacement vector from the second candidate vectors and the first candidate vector group, and a motion vector arithmetic part 7 determines a motion vector of the detecting object block with the initial displacement vector as a start point through one or more operations.