A lamp reflector having a substrate in which desired surface smoothness and rigidity are ensured, while the dimensional accuracy is high. Also, a method of manufacturing such a lamp reflector. In order to ensure surface smoothness, rigidity, and high dimensional accuracy, the lamp reflector is provided with a substrate made of a composition containing at least polyphenylene sulfide resin (PPS resin), synthetic calcium carbonate whiskers, and synthetic calcium carbonate (CaCO3). And the method for manufacturing this lamp reflector includes injection molding using high-pressure gas.