A transparent member 2 defines part of a lamp compartment 4. A light source 5a is accommodated within the lamp compartment 4 and shines light to the front through the transparent member 2. A detection device 6 is accommodated within the lamp compartment 4 and obtains information on what exists ahead. A stepped portion 7 is formed on an external surface of the transparent member 2 and guides drops of water which adhere to the external surface so as to avoid a detection enabled area of the detection device 6.