To provide a noble gas fluorescent lamp with a light utilization rate improved, free from problems of a positional slip of a lamp caused by a fixing method at a lamp holder part or contact failure due to volatilization of low-molecular siloxane in an adhesive even with a temperature rise at a tube wall.

Of the noble gas fluorescent lamp with a pair of electrodes arranged in opposition at an outer wall of a straight-tube glass bulb along a tube axis direction, with noble gas containing xenon gas as a main component sealed in the bulb, with a phosphor layer formed over a whole length of a bulb inner wall in the tube axis direction except at an aperture part, and with a lamp holder fitted at an end part of the bulb, the lamp holder is composed of an aperture positioning member for setting an aperture opening position and a lamp fixing member for fixing the lamp, of which the aperture positioning member, of cross-section C-shaped resin, is fixed to the noble gas fluorescent lamp by a heat-shrinkable tube, and is fitted into and fixed to the lamp fixing member.