A chip carrier includes a metal-coated portion formed on a front surface of a substrate and to be mounted a device, and a rear surface of the substrate being coated with a metal, in which a metal-coated portion is formed on a side surface of the substrate and the metal-coated portion on the front surface of substrate is connected with the metal-coated portion on the rear surface by the metal-coated portion formed on the side surface of the substrate, thereby maintaining frequency characteristics of the optical semiconductor device.