PERISCOPE

PROBLEM TO BE SOLVED: To obtain a small-sized inexpensive periscope which enables an observation to be made from a floor level by using a telescope, can narrow down the movement range of an observer accompanying the movement of the telescope, and makes it possible to change the direction of the telescope fast. SOLUTION: The periscope 31 is equipped with a collimator lens part 32 which emits as a parallel light beam a diverged light beam which is made incident from a 1st image formation surface, an ocular part 33 which has a 1st imaging lens for imaging the parallel light beam emitted from the collimator lens on a 2nd image formation surface, and a moving mechanism 34 which enables the ocular part 33 to move to and away from the collimator lens part 32, and the collimator lens is so constituted that the luminous flux of the whole visual field made incident on the 1st imaging lens has the smallest diameter at the center part of the movement range of the 1st imaging lens.