PURPOSE: To increase the strength of filament and to improve the ease of assembling, by fixing the spacer to prevent the vibration of cathode filament to the center support with Mo sintering body.

CONSTITUTION: In the magnetron cathode constituent, providing the upper and lower end shields 2 and 4 respectively fixed to the upper and lower end of the cathode filament 1, the center support 3 leading to the center of the upper and lower shields 2 and 4 and the side support 5 fixing its one end to the lower shield 4, and the spacer 10 preventing the vibration of the supports 3 and 5, the hole 11 through which the support 3 is passed to the spacer 10 is provided and the external part is fitted to the mating part 12 with step on the shield 4. Further, Mo fine powder is coated on the fixing part of the spacer 10 of the support 3 after mixing it with binder and the spacer 10 is fixed with the Mo sintering body 13 by sintering the coating material. Moreover, in another example of execution, the spacer 10 is clipped and fixed with the shields 2 and 4.