PURPOSE: To stably transfer an electron gun by providing a positioning means for an electron gun and a stopper for preventing the displacement of the electron gun besides a retaining means for retaining the electron gun.

CONSTITUTION: First, a transferring means, a hand 5 in particular, is moved to the side of an electron gun 10 placed on a supporting mount, and also a stopper 15 is slid to the side of an arrow (b). Then a claw 14 is inserted between a fourth grid electrode G4 and a fifth grid electrode G5 to make the positioning of the electron gun 10 to settle the position of the electron gun before starting transfer. After that, the hand 5 is closed to fix the electron gun 10 positioned between rolls 5a. Finally the stopper 15 is slided in a (a) direction to abut on the end surface position of the first grid electrode pad 1 of the electron gun 10 to be stopped and fixed, completing fixing the electron gun by the above respective actions. Consequently the displacement and falling accident of the electron gun at the time of transfer can be prevented.