To provide an optical network service of a shortest transmission delay time effectively utilizing a high-speed property of optical fibers.

The present invention comprises an optical fiber, an optical hub and an optical network interface circuit (optical NIC), the optical NIC transmits a communication signal instructed to be transmitted from a user terminal by means of an optical signal, that optical signal is broadcasted over the network by the optical fiber and the optical hub and at a receiving terminal side, the optical NIC receives the optical signal, restores the original communication signal and delivers it to the user terminal. As an optical media access mode, a semi-fixed access mode and a multiplex access mode are included and in operation during the semi-fixed access mode, the transmitting-side optical NIC includes a device for selection from the combination of a plurality of transmission light wavelengths and a plurality of time slots to carry a transmission signal thereon.