Abstract: The present invention relates to a technology for enabling each user's PC to transmit a packet separately through an internal network or external network by means of a virtual private network almost without changing the existing network environment in a network division system for physically dividing PCs into a group for accessing the internal network and a group for accessing the external network. To this end, the present invention does not allow the connection between an internal network PC and an external network PC through a network division apparatus, does not allow the internal network PC to connect to an encoded gateway, and does not allow the external network to connect through the encoded gateway to the internal network, but enables the internal network PC to connect to the internal network, and the external network PC to connect through a virtual private network to the external network.