Optical axes are simultaneously adjusted by tiltably mounting a plurality of lighting device units on a common unit support member. A rectilinear propagation blocking member of each lighting device unit is fixed with screw via the elastic bush to the unit support member, so that the optical axis can be adjusted. Due to the above structure, even when the accuracy of shapes of the rectilinear propagation blocking member and the unit support member are not sufficiently ensured and also even when the accuracy of the attaching work can not be sufficiently ensured, the optical axes of the lighting device units can be arranged in order by adjusting the optical axis of the rectilinear propagation blocking member.