In a discharge lamp device, the arc tube body is configured by welding and integrating
shroud glass with an arc tube so as to enclose a discharging portion, and a rearward
elongating portion of the arc tube that elongates in the rear of the shroud glass
is inserted and held into an opening of an insulating plug which is made of synthetic
resin. A UV blocking film is formed on the outer surface of the rearward elongating
portion of the arc tube. UV components of leakage light from the rearward elongating
portion are cut off, and the amount of ultraviolet rays to which the resin layer
in the opening is exposed is reduced. The UV blocking film is in the opening, and
hence cannot be seen through a front lens.
