To provide a switching hub and a quarantine network system that can restrain communication between terminals in an isolated network in the case that a business network and the isolated network are constructed of a VLAN.

A switching hub with a VLAN function 20 connected to a management server managing a network is used. The switching hub 20 comprises: a VLAN setting unit 201 for setting a VLAN, which is the connection destination of a terminal connected to the switching hub 20, to either a VLAN for business or a VLAN for isolation according to an instruction from the management server; a packet processing unit 210 which receives a packet transmitted from a terminal, determines whether communication between terminals in the VLAN for isolation is performed based on the MAC address of a transmission source and the MAC address of a transmission destination of the received packet, and if the communication is performed, discards the received packet.