Grooves (22, 23) for containing an optical fiber and five recesses (24) for containing the optical components for an optical fiber amplifier are provided in the surface of a substrate (21). An optical fiber fitted in a groove (23a) for containing the optical fiber and introduced to the substrate (21) is passed through a groove (22a) for containing the optical fiber and fitted in a groove (22) for containing the optical fiber, thence passed through a groove (22b) for containing the optical fiber and introduced to the outside of the substrate (21). In the recess (24) for containing the optical component for an optical fiber amplifier, an optical component such as a photocoupler is fitted and coupled with the optical fiber. Light such as pumping light is passed through an optical fiber contained in the groove (23) for containing the optical fiber and introduced to an optical component such as a photocoupler. When the optical fiber and the optical component for an optical fiber amplifier are contained in such a recess of the cassette, they can be contained orderly.