PURPOSE: To improve the reliability of maintaining the vacuum degree by providing a getter membrane for gas absorption purpose at the inner wall of an image tube.

CONSTITUTION: A bulb main body 100 and a photoelectric screen plate 3 are set at different positions, and the inside of a vacuum chamber is evacuated. The photoelectric screen 2 is formed in a photoelectric screen forming member 16. In this case, a getter movement manipulator 18 with a flash getter 19 installed at the tip is lowered to evaporate the flash getter 19 at a specific position in the bulb main body 100, to form a getter film 1. After that, the getter movement manipulator 18 is lifted, the photoelectric screen plate 3 is moved, and the bulb main body 100 is sealed up. By forming the getter film 1 in such a way, an image tube requiring no getter wire and no current feeding electrode to the getter wire in the structure can be supplied. Consequently, the reliability in respect to maintaining the vacuum degree by reducing the soldered parts can be improved.