To provide a lamp in which the outside appearance of the lamp when lighted is improved and the strength in each portion of the lens of the lamp is made uniform, thereby which can be used for an equipment having large vibrations such as vehicles.

A first step 16 which has curved faces 15, 26 that are concave or convex curved line in cross sectional edge when viewed in the X direction and extending in the X direction of the surface of a lens 13 is formed on the surface of the lens 13. The first step 16 is continuously provided along the surface of the lens 13 and in the orthogonal direction Y which crosses at right angles the X direction. A plurality of second steps 18 which have two inclined flat surfaces 17, 17 of cross sectional V-shape edge when viewed in the orthogonal direction Y are formed on the curved faces 15, 26 of the first steps 16. These second steps 18 are provided in the longitudinal direction of the first steps 16.