According to the structure of the present invention, the structure is improved as the mobile radiation device can be assuredly stopped on the horizontal pathway without jounce. Specifically, the present invention provides the idea in the case of moving on the slope pathway Specifically, the braking control element 18 turns the brake module 19 operative when the velocity of the wheeled platform increases despite beginning of braking the wheeled platform 1 by the velocity lowering control element 17. In such cases, according to the present invention, despite beginning of braking the wheeled platform 1 by the velocity lowering control element 17, when the velocity of the wheeled platform 1 increases, the brake module 19 is turned operative promptly so that the incident in that the wheeled platform 1 continues to move for a long time ignoring the direction to stop the wheeled platform 1 moving on the slope can be controlled.
