First direction ridge patterns and second direction ridge patterns are lined-up alternately at a decorative concave portion 18. Plural main ridges 22A through 22D and sub-ridges 26A through 26D, which project-out from a bottom surface 18A, are formed at a first direction ridge pattern 20. The respective ridges are disposed in parallel such that ridge extending directions are a same direction. Light reflection patterns are different at a main ridge region 24, 34 and a sub-ridge region 28, 38.