A network device configured to be connected with a network, the network device comprising: a PHY layer process unit configured to execute a process of a PHY layer; a MAC layer process unit configured to execute a process of a MAC layer; a determination unit (36, 38) configured to determine that a link state is a link up state or a link down state by utilizing information given from the PHY layer process unit, wherein the link up state is a state in which the network device is being connected with the network in a communicable manner, and the link down state is a state in which the network device is not being connected with the network in a communicable manner; and a first control unit (36, 38) configured to control an electrical power supply for the MAC layer process unit; and a second control unit configured to shift between a sleeping state and a non-sleeping state; wherein the first control unit (36, 38) is configured to: stop a continuous electrical power supply for the MAC layer process unit, if the determination unit (36, 38) determines that the link state is the link down state and the second control unit is in the sleeping state; and commence the continuous electrical power supply for the MAC layer process unit, if the determination unit (36, 38) determines that the link state is the link up state; wherein an electrical power supply for the PHY layer process unit is continuously performed, regardless of the link state, wherein the first control unit (36, 38) is configured to further commence the continuous electrical power supply for the MAC layer process unit regardless of the link state, when the second control unit shifts from the sleeping state to the non-sleeping state. a PHY layer process unit configured to execute a process of a PHY layer; a MAC layer process unit configured to execute a process of a MAC layer; a determination unit (36, 38) configured to determine that a link state is a link up state or a link down state by utilizing information given from the PHY layer process unit, wherein the link up state is a state in which the network device is being connected with the network in a communicable manner, and the link down state is a state in which the network device is not being connected with the network in a communicable manner; and a first control unit (36, 38) configured to control an electrical power supply for the MAC layer process unit; and a second control unit configured to shift between a sleeping state and a non-sleeping state; stop a continuous electrical power supply for the MAC layer process unit, if the determination unit (36, 38) determines that the link state is the link down state and the second control unit is in the sleeping state; and commence the continuous electrical power supply for the MAC layer process unit, if the determination unit (36, 38) determines that the link state is the link up state; wherein an electrical power supply for the PHY layer process unit is continuously performed, regardless of the link state, wherein the first control unit (36, 38) is configured to further commence the continuous electrical power supply for the MAC layer process unit regardless of the link state, when the second control unit shifts from the sleeping state to the non-sleeping state.