A luminous keyboard includes a cap which has a bottom lid with a first light directing zone formed thereon. The cap also has a first light blocking surface on an outer surface corresponding to the first light directing zone. At least one luminous unit is provided to provide light to the first light directing zone so that the light projects to the first light directing zone is diffused and blocked by the first light blocking surface, and finally projected to a keyboard portion to illuminate keycaps. The bottom lid replaces the light directing layer used in the conventional luminous keyboards. Thus the interior space of the keyboard can be shrunk to make fabrication and assembly of the keyboard simpler. The keyboard thus formed is thinner and lighter and suitable for mass production.