To perform a continuously variable speed change or a multistage speed change with a compact and light-weight device by providing one of a pair of rotary bodies disposed so as to be rotated relatively to each other to be circular plate-like having a slope and providing an intermediate member slid along the slope in the other rotary body.

When the rotary body 1 of an input side is rotated, a slope 3 formed in its cylindrical inner surface applies a force to an intermediate member 4. For the sliding of the intermediate member 4, since limit is applied to oil injected in a space formed by the cylindrical inner surface of a rotary body 2 and a notch by a projection, the intermediate member 4 is moved in the rotational direction of the rotary body 1 like being pulled while being moved in a sliding direction. Thus, the rotary body 2 holding the intermediate member 4 is rotated and the rotation of the rotary body 1 is transmitted to the rotary body 2. When the rotary body 2 is moved by a displacing device 7 in this condition, since the angle of the slope 3 is increased and the degree of pulling the intermediate member 4 in the rotational direction of the rotary body 1 is increased, the rotational ratio of the rotary body 2 is increased.