To allow a user to easily, inexpensively and naturally train the vision while sleeping at home or taking a rest at an office.

An observer located on the floor observes a flying toy hanging from a ceiling with a string. The flying toy performs the circular flight determined by the dynamic balance among the thrust force, gravity and lift force while hung with the string. Then, the speed of the flying toy is gradually increased, the radius of the circulation is gradually increased, and the height from the floor surface is gradually increased. After that, the speed is gradually lowered, the radius of circulation is gradually reduced, and the height from the floor surface is gradually lowered. Further, the string is gradually taken up into the flying toy, and the string gradually becomes shorter and the height of the flying toy from the floor surface is gradually increased. Then, as the flying toy is restrained by the length of the string, the radius of circulation is gradually reduced. Next, the string is rewound from inside the flying toy, and the string gradually becomes longer and the height from the floor surface is gradually lowered. Then, in proportion to the length of the string, the radius of circulation becomes slightly larger. The flying toy repeats the circular flight, and the observer observes the flying toy with the eye.