1. An image processing device that performs image registration processing between a plurality of images through a motion vector calculation, comprising: a motion vector measurement region setting unit for setting a plurality of motion vector measurement regions for which a motion vector is measured; a motion vector calculation unit for calculating the motion vectors of the plurality of motion vector measurement regions; a motion vector reliability calculation unit for calculating a reliability of the respective motion vectors; a main region setting unit for setting a main region in relation to at least one image of the plurality of images; and a motion vector integration processing unit for calculating an inter-image correction vector by integrating the motion vectors of the plurality of motion vector measurement regions, taking into account the reliability, wherein the motion vector integration processing unit includes a contribution calculation unit for calculating a contribution of the respective motion vectors from a positional relationship between the respective motion vector measurement regions and the main region, and integrates the motion vectors of the plurality of motion vector measurement regions in accordance with the reliability and the contribution.