1. An endoscope system for taking images of an inside of an object, comprising: an omnidirectional camera operable to take a plurality of images of the inside of the object in a living body, which is capable of motion; and an image generation unit operable to generate a panoramic image of the inside of the object by performing a video mosaicking process, a motion correction process, and an image modification process through energy minimization on the plurality of images obtained by said omnidirectional camera, said processes being intended for pasting the images, estimating camera motion, correcting previously definable motion in the living body, and correcting previously indefinable internal deformation in the living body, wherein said image generation unit is operable to generate the panoramic image such that the panoramic image has a fixed visual angle with respect to each of directions perpendicular to a traveling direction of said omnidirectional camera, by performing the video mosaicking process on the plurality of images obtained by said omnidirectional camera, wherein said image generation unit includes: a feature region cutout unit operable to cut out a plurality of feature regions having a predetermined size from each of the plurality of images obtained by said omnidirectional camera; and a panoramic image generation unit operable to define energy based on the plurality of feature regions included in each of the plurality of images, associate the plurality of feature regions between the plurality of images such that the energy is minimized, and generate a panoramic image of the inside of the object based on the association result, and wherein the plurality of feature regions are regions which are included in the plurality of regions having the predetermined size included in each of the images, and in which a squared sum of derivatives of pixel values is greater than a predetermined threshold value.