PURPOSE: To enable the fixed amount of mercury to be accurately dropped and enclosed into the captioned lamp, by maintaining the enclosed substance fed from a nozzle having a shut-off valve for receiving the substance enclosed in the lamp, and installing a rotary shaft for further dropping the enclosed substance to the lower part and an exhaust port connected to a vacuum-exhaust system.

CONSTITUTION: Above the upper part of an exhaust head 2 is a nozzle 9 which performs a vertical motion through a lever 8 by means of an external actuator; while the nozzle 9 is ascending, mercury grains 11 dropped from an external mercury dropping device 10 is fed onto a mercury receiver 16 of a rotary shaft 17 through the connecting-hole 12 of the nozzle 9, said mercury receiver 16 being made of a concave part which is rotatable by means of a lever 15 connected to the outside and installed within the chamber 13 of the exhaust head 2, said chamber 13 being hermetically sealed to the outside by an O ring 14. At a station where the mercury grains 11 are to be enclosed into a discharge lamp 3, the rotary shaft 17 is rotated by the external actuator, and the mercury is dropped and sealed thereinto by reversing the concave mercury receiver 16.