1. An image processing apparatus comprising: an adjacent region setting unit that sets spatially adjacent regions on the basis of positions of prediction regions in a coding region so that generation of spatial motion vectors of the plurality of prediction regions is performed in parallel when a spatial prediction motion vector is generated among prediction motion vectors used to decode motion vectors of the plurality of prediction regions forming the coding region of an image; a prediction motion vector generation unit that generates a spatial prediction vector of the prediction region by using the motion vector of the spatially adjacent region set by the adjacent region setting unit; and a motion vector decoding unit that decodes a motion vector of the prediction region by using the prediction motion vector of the prediction region.