PURPOSE: To improve the accuracy of mercury-sealing into the captioned lamp, by installing a nozzle for receiving mercury having a shut-off valve and a rotary shaft for dropping it, and connecting the most upper part of the vacuum chamber within the exhaust head to the exhausting system.

CONSTITUTION: A main body rotating table 1 has plural exhaust heads 2, and the exhaust pipe 4 of a discharge lamp 3 is hermetically kept by means of an elastic rubber body 5. In compliance with a specified exhaust schedule, after mounting the discharge lamp 3, exhausting operation, and washing and exhaust by argon gas are carried out through an exhaust nipple 16 installed just over an exhaust chamber 13', then a rotary shaft 15 is forced to rotate, at a station where the predetermined degree of vacuum is obtained, mercury grains kept on a mercury receiver 14 are dropped and introduced into the discharge lamp 3 through the exhaust pipe 4, while pouring argon gas from the exhaust nipple 16 thereinto.