PURPOSE: To regulate the thickness of the coating on the top part of a material to be painted to an appropriate thickness by providing a means for changing the spraying posture of a painting gun for the direction passing a part of the sprayed paint through the material to be painted.
CONSTITUTION: A helmet 5 is turned around a vertical axis in correspondence with the revolution of a driving roller 33 rotated by a motor 42 which is pressed against the cam surface 32 of a cam plate 31 coupled with a rotary body 3. Meanwhile, a painting gun 8 is elevated upward by an elevating means 47 from the lowermost position, and the outer surface of the helmet 5 is coated with the paint sprayed from the painting gun 8. In painting, the cam surface 32 of the cam plate 31 has a shape analogous to the outer circumferential surface of the helmet 5, and the peripheral speed of the outer circumferential surface of the helmet 5 is made constant. The outer surface of the helmet 5 is sprayed with the paint in a specified thickness in this way.