To improve operability in acceleration and deceleration in a mobile body.

The mobile body can move in the longitudinal direction according to the movement of gravity center in the mobile body in the longitudinal direction. The mobile body includes: a vehicle body; a stepping part supported onto the vehicle body tiltably in the longitudinal direction; and an operating unit for operating the tilting of the stepping part in the longitudinal direction. Thus, the stepping part can be tilted based on the operation of the operating unit performed by a person on board to assist the movement of gravity center by the person on board, thereby improving the operability of the mobile body.