1. A method of generating an interpolated image at a user viewpoint position different from first and second viewpoint positions on the basis of first and second images obtained at the first and second viewpoint positions, comprising: the first correcting step of correcting the first and second images about the first and second viewpoint positions, respectively, such that optical axes of cameras which respectively sensed the first and second images coincide with a first direction substantially coinciding with a direction of a base line connecting the first and second viewpoint positions; the first coordinate interpolation step of calculating coordinates of a corresponding point of an interpolated image having the first direction as a line of sight direction at the user viewpoint position by performing nonlinear proportional distribution for coordinates of a first corresponding point in the first image with respect to a predetermined feature point and coordinates of a second corresponding point in the second image with respect to the feature point; and the second rotation step of rotating the interpolated image from the first direction to the line of sight direction at the user viewpoint position, and outputting the image after correction as an interpolated image.