A transparent resin plate includes a plurality of slits formed intermittently and located along the border line between a housing frame portion and a light conductor plate portion, the slits includes either or both of respective first optical path converting portions and a second optical path converting portion, and flap portions of a reflector are inserted at least in the first optical path converting portions. Also, the second optical path converting portion of the plurality of slits is arranged to meet at least part of optical paths of hypothetical optical paths which are emitted forward from a light source in the forward direction, reach directly the housing frame portion and which do not cross the first optical path converting portion.