PURPOSE: To change the direction and angle of a sign display surface according to the conditions of location by providing a display body which is stood and supported swinging upward from the horizontal direction through an elevation device rotating horizontally and can changes displays on the roof of a vehicle.

CONSTITUTION: A rotary disk 23 is provided which is rotated horizontally by a rotary driving device 20 mounted and fixed on a base plate 21 provided on the roof 2 of the vehicle, and further the display body 40 is provided which is stood and supported swinging up from the horizontal direction through the elevation device 30 fixed on the top surface of the rotary disk 23 and can change displays. The range of vertical swinging by the elevation device 30 is set within a range exceeding the vertical direction from the horizontal direction, so various pieces of information under special environment are adapted to the time and place and the display body 40 can be supported in such a direction and at such an angle that the displays are easy to see.