PURPOSE: To enable a multi-layer cathode sleeve for a long life oxide cathode to be obtained by forcibly pressing a cup-state body structure to a cylindrical sleeve body structure by applying pressure to both body structures made unitedly.

CONSTITUTION: A cylindrical sleeve body structure 2 which is made to be a substrate metal is formed by only a nickelchrome alloy and furthermore a cup-state body structure 1 having a whole shape adaptable to a tip opening part of the cylindrical sleeve body structure is formed and prepared by only a cathode nickel. In this case a mouth edge of the cup-state body structure 1 has a ring-state expansion part 1a. The cup-state body structure 1 of nickel is engaged and united with a tip closing part of the cylindrical sleeve body structure 2 of the nickel-chrome alloy, placed on an under side die 3 of a super hard metal of a pressure device, an upper side die 4 of the super hard metal is made to descend in a moment, and thereby a shockingly high pressure F is applied to the cup-state body structure 1. A cathode sleeve in which both body structures are firmly united is obtained with the cup-state body structure 1 forcibly pressed in or pressed to the cylindrical sleeve body structure 2.