A home network system comprising a plurality of content usage devices that are connected to one another via a communication network and use a content which is a digital work, at least one of the plurality of content usage devices holding license information sent from outside the home network system in a license management unit, and wherein each of the content usage devices is configured to authenticate a license management unit that requests the license information from another content usage device of the plurality of content usage devices, wherein a content usage device includes: a license information acquisition unit operable to acquire the license information from the at least one content usage device holding license information, said license information enables usage of a content; and an output unit operable to use a content in compliance with the acquired license information and output the content in at least one manner of a sound, video and data, Wherein the license information acquisition unit is operable to search for the license management unit of the at least one content usage device holding license information, the search being performed by either a broadcast method of inquiring to all the license management units simultaneously about whether they hold the requested license information, or by a sequential access method of inquiring to the license management units individually and sequentially about whether they hold the license information, or by a prior push method of storing what kind of license information is held in each license management unit, or a search commission method of commissioning one of the license management units to search for the license information and then commissioning another license management unit to search for the license information when the former does not hold it, and to acquire the license information from the at least one content usage device holding license information. a license information acquisition unit operable to acquire the license information from the at least one content usage device holding license information, said license information enables usage of a content; and an output unit operable to use a content in compliance with the acquired license information and output the content in at least one manner of a sound, video and data, Wherein the license information acquisition unit is operable to search for the license management unit of the at least one content usage device holding license information, the search being performed by either a broadcast method of inquiring to all the license management units simultaneously about whether they hold the requested license information, or by a sequential access method of inquiring to the license management units individually and sequentially about whether they hold the license information, or by a prior push method of storing what kind of license information is held in each license management unit, or a search commission method of commissioning one of the license management units to search for the license information and then commissioning another license management unit to search for the license information when the former does not hold it, and to acquire the license information from the at least one content usage device holding license information.