The invention relates to an EPON bridge apparatus and a forwarding method thereof. In a case of receiving a frame from the network port or the PON port, the apparatus associates the port having the received frame inputted with a source MAC address of the received frame to learn the information in an FDB table, which manages port information for the learned MAC address. Then the apparatus refers to the FDB table to remove an LLID from upstream frame, and then forwards the upstream frame to the network port, while attaching an LLID corresponding to a destination MAC address to the downstream frame to transmit to the PON port. Bridging between ONUs is possible with flooding capability using an anti-LLID. VLAN-LLID translation mode is provided with support for VLAN tag addition/removal at the ONU side. A multicast pruning function is provided for the downstream.