A slave device is realized that establishes a link with a master device or another slave device such that a large link delay hardly occurs. The slave device includes a PHY unit, a COM unit, and a MPU unit. The PHY unit starts an operation according to the specification of the AutoMDI/MDI-X function when the slave device is turned on or the PHY unit itself is reset. After a predetermined time period has elapsed, the MPU unit resets the COM unit, and the PHY unit is reset in response to the reset of the COM unit.