A node device having a plural hierarchy levels in a tree-like shape while placing a broadcast device at a top of the levels and connecting the node devices through a communication means, wherein content data is sequentially transferred from the node device at an upper hierarchy level to that at a lower hierarchy level, including: a control means for displaying a predetermined screen for a user; and a means for carrying out a process of participating in the system when a broadcast information screen related to broadcast of the content data is displayed and for carrying out a process of withdrawing from the system when display is finished, wherein when transiting to display in another screen, the participation and withdrawal control means carries out the withdrawal process on a condition that the broadcast information screen is not displayed again within a waiting time previously set up.