1. An image matching method for matching a first image and a second image, comprising: a first step for performing image conversion processing based on a distance from a reference position in each of said first image and second image and an angle formed by a straight line passing through said reference position and a reference axis including said reference position and generating a first converted image and a second converted image in a two-dimensional space defined by said distance and said angle, and a second step for performing matching processing of said first image against said second image based on results of the correlation processing at a plurality of different relative locations in a first direction and a second direction orthogonal to said first direction in the first converted image and second converted image generated at said first step.