<p>The circuit sections constituting an OLT (10) are divided in advance into one constantly-powered block (B0) and one power saving block (B1). A power supply control section (40) always supplies power to the circuit sections belonging to the constantly-powered block, and starts supplying power to the circuit sections belonging to the power saving block at timing determined on the basis of the start timing of an upstream band period assigned to each ONU and stops supplying the power at timing determined on the basis of the end timing of the upstream band period. As a result, the power consumption of the entire OLT is reduced.</p>
