A branch portion of a socket is formed into a thin cylindrical shape so
that it can be elastically displaced, end faces of both side plates of a
lamp reflector are made to be points for positioning, positioning
protrusions are integrally protruded from both side outer end edge
portions of each socket body, under the condition that a substantially
L-shaped through-passage of each socket is externally engaged with each
lead wire, an end portion of each lead wire is brazed to both end
portions of a straight-pipe-shaped light source, when each socket is slid
along each lead wire, each socket covers a region from the end portion of
each lead wire to the end portion of the straight-pipe-shaped light
source, and each socket body is inserted into a lamp reflector so as to
make a positioning protrusion come into contact with a positioning point.