To provide an innovative technology that accumulates energy in braking applied to a rotator, can use the energy for restart or acceleration of the rotator, and continuously operates a brake to the rotator even when the energy amount excesses an accumulable energy amount.

A movable body controller comprises a first rotator 1 rotated by a rotating shaft 4, a second rotator 2 that can contact with and separate from the first rotator 1 and is rotated by the rotating shaft 4, an accumulating mechanism for accumulating the energy when the first rotator 1 abuts on the second rotator 2, and a differential rotating mechanism for rotating the second rotator 2 at a rotation speed different from that of the first rotator 1. When the energy is accumulated, the energy is applied as a load to decrease the rotation speed of the first rotator 1, and thus the rotation speed of the rotating shaft 4 is decreased. When the second rotator 2 is rotated at the rotation speed different from that of the first rotator 2 in an abutting state of the first rotator 1 on the second rotator 2, the rotation speed of the rotating shaft 4 is decreased.