This invention relates to an apparatus and method for setting up groups in a home network system. One embodiment of the method involves two or more home appliances and a user terminal constituting the home network system. The method includes: a user terminal setting up a group for two or more home appliances and sending a first message to a master device in the home appliances notifying it that it is the master device of the group, and a second message to a slave device in the home appliances notifying it that it is the slave device of the group; the master device and the slave device respectively receiving the first and second messages and then sending and receiving Internet Protocol Layer (IPL) messages to perform a discovery process; and the master device and the slave device sending and receiving Application Layer (ALL) messages after the discovery process to perform a grouping process.