The invention relates to an reimaging optical system that has a sufficiently enhanced magnification and better performance, and an endoscope using the same. The reimaging optical system 3 is adapted to re-form an image by an image guide 6 on a solid-state imaging device 4 having a diagonal length of 6.5 mm or longer, and satisfies the following condition.0.6<(D×|β|)/V (1).Here D is the diameter of the image guide 6, β is the optical transverse magnification of the reimaging optical system 3, and V in mm is the minor axis direction length of an imaging area of the solid-state imaging device 4.