Fuente: Wipo "IOT" A closed home IoT service system using blockchain according to the present invention comprises: a communication module electrically connected to an external Internet network; a messenger unit connected to the communication module and receiving IoT-related data including at least one of an IoT control signal and an application update transmitted from the outside; and a plurality of IoT devices connected to the messenger unit through an internal network and divided into a main member whose power consumption is above a certain threshold and a sub-member whose power consumption is below a certain threshold. Among the plurality of main members, any one of the main members selected as a master member overseeing the plurality of IoT devices selects one of the other main members as a master member after a certain time elapses. The messenger unit transmits an event signal indicating that there is a request to receive the IoT-related data from the outside for the plurality of main members. The master member receives an IoT-related data receiving request event signal and then receives the IoT-related data from the messenger unit. Each of the main member and the sub-member may share blockchain data including a change history of a master member, an update history of the IoT software version of the plurality of IoT devices, and a control history of the plurality of IoT devices. Accordingly, provided is a home IoT service system having an authentication means capable of clearly authenticating an external control signal. COPYRIGHT KIPO 2020