1. An image processing device comprising: a matching degree calculation unit configured to calculate a matching degree between a pixel value of a target pixel in a standard image of a current frame and a pixel value of a corresponding pixel in a reference image of the current frame; and an estimation unit configured to estimate a disparity between the standard image and the reference image based on a result obtained by calculating the matching degree, wherein the matching degree calculation unit calculates the matching degree using a disparity estimated for the standard image and the reference image of a previous frame.