PURPOSE: To facilitate replacement of component parts in a globe by coupling the base with one end of a set ring by a coupling means which is rotatable, securing the other end of the set ring to the base by a securing means which is capable of being mounted and removed, and thus installing the set ring.

CONSTITUTION: When a screw 11 is set off from a threaded hole 7a in a projection 7 provided on a base 2, a set ring 4 is made rotatable round a supporting shaft 18 as fulcrum on which a detention part 9 is hitched. A flange 8 on a globe 3 is released from a glange 4a on the set ring which holds the flange 8 and the globe 3 can be removed from the base 2 so that replacement of electric bulb 14 is made easier. By a washer 12 the screw 11 is supported rotatably on the bottom plate 10a of a recess 10 in the set ring 4 so that there is no risk of missing.