A keyboard includes a number of buttons for being actuated by users, and includes a space formed between the buttons, and includes an electric circuit. One or more illuminating members and one or more optical elements are disposed on the space of the keyboard and disposed close to each other. The illuminating member is coupled to the electric circuit of the keyboard and to be energized to generate light through the optical element, and to light the buttons of the keyboard. The illuminating members are not required to be electrically coupled to the other electric power source separately.