An autonomous mobile body is configured to smoothly avoid obstacles. The mobile body has a movement mechanism configured to translate in a horizontal plane and rotate around a vertical axis, and the distance to an obstacle is derived for each directional angle using an obstacle sensor. Using a model having two arcs, one at each end in a major axis direction, connected by line segments that lie in the major axis direction and containing the autonomous mobile body, the movement mechanism is driven with a combination of translation and rotation, without interference between the obstacle and the model.