An IoT-based thing management system using block chain authentication wherein a plurality of unit nodes (ND1, ND2, ND3, ND4) connect to each other through at least one of wire communication network and wireless communication network, things (D11, D12, D13, D21, D22, D23, D31, D32, D33, D41, D42, D43) connect to each other in each of the unit nodes, and control instructions for causing the things to be operated are mutually authenticated by the plurality of unit nodes so as to confirm the validity of the instructions; wherein each of the unit nodes (ND1, ND2, ND3, ND4) comprises: a plurality of things(D11, D12, D13, D21, D22, D23, D31, D32, D33, D41, D42, D43) which connect directly or indirectly to at least one of the wire communication network or the wireless communication network, each of the things performing individual functions separately; and a core (C10, C20, C30, C40) which includes an n block chain having n blocks, n is a natural number, recording operation histories of the things thereon, the blocks being linked one after another in the form of a chain, and the core is configured to generate unique public keys and unique private keys based on the n block chain and provide the generated keys to each of the things, wherein one of the plurality of the things includes a controller (CT10, CT20, CT30, CT40) which has a list of public keys provided by the core, each of the public keys is unique to each of the things, the controller is configured to send a control instruction with the controller's private key combined thereto, to a thing of which a public key is selected by the controller from the list of the public keys, so as to control operations of the thing based on the sent control instruction, and the thing is configured to send the controller a response signal with the thing's private key combined thereto in response to the control instruction and perform an operation according to the control instruction; and wherein at least one of the control instruction with the controller's private key combined and the response signal with the thing's private key combined includes an n+1-th block which has a block hash including an encrypted hash of the effective n-th block, the n+1-th block is spread to the nodes, and the n-th block hash is previously approved and confirmed by the plurality of nodes. a plurality of things(D11, D12, D13, D21, D22, D23, D31, D32, D33, D41, D42, D43) which connect directly or indirectly to at least one of the wire communication network or the wireless communication network, each of the things performing individual functions separately; and a core (C10, C20, C30, C40) which includes an n block chain having n blocks, n is a natural number, recording operation histories of the things thereon, the blocks being linked one after another in the form of a chain, and the core is configured to generate unique public keys and unique private keys based on the n block chain and provide the generated keys to each of the things, wherein one of the plurality of the things includes a controller (CT10, CT20, CT30, CT40) which has a list of public keys provided by the core, each of the public keys is unique to each of the things, the controller is configured to send a control instruction with the controller's private key combined thereto, to a thing of which a public key is selected by the controller from the list of the public keys, so as to control operations of the thing based on the sent control instruction, and the thing is configured to send the controller a response signal with the thing's private key combined thereto in response to the control instruction and perform an operation according to the control instruction; and wherein at least one of the control instruction with the controller's private key combined and the response signal with the thing's private key combined includes an n+1-th block which has a block hash including an encrypted hash of the effective n-th block, the n+1-th block is spread to the nodes, and the n-th block hash is previously approved and confirmed by the plurality of nodes.