A remote service system for changing setting conditions of a facility arranged in a plant from a remote place comprising: a first computer terminal configured to add a first signature to control information representing change information representing change content for changing a setting condition of the facility (320a-320c) in the plant to be applied to the facility (320a-320c) of the plant and transmit the control information to a third computer terminal via a first communication network; a second computer terminal configured to cause the change content for changing the setting condition of the facility (320a-320c) arranged in the plant represented by the control information to be applied to the facility (320a-320c); and the third computer terminal configured to further add a second signature to the control information and transmit the control information to the second computer terminal via the first communication network when the first signature added to the control information is a correct signature and the control information represents the change content for changing the setting condition of the facility (320a-320c) arranged in the plant applicable to the facility (320a-320c), wherein each of the first computer terminal, the second computer terminal and the third computer terminal are connected to the first communication network, wherein the second computer terminal and the facility (320a-320c) are connected by a second communication network, wherein the first computer terminal is configured to receive the change content for the facility (320a-320c), add the first signature to the change information representing the received change content, and transmit the change information, wherein the third computer terminal is configured to further add the second signature to the change information and transmit the change information when the first signature added to the change information is a correct signature and the change information represents the change content applicable to the facility (320a-320c), wherein the second computer terminal is configured to cause the change content represented by the change information to be applied to the facility (320a-320c) of the plant, wherein the first communication network is a communication network in which a block chain is constructed, and wherein the second communication network is a dedicated communication circuit. a first computer terminal configured to add a first signature to control information representing change information representing change content for changing a setting condition of the facility (320a-320c) in the plant to be applied to the facility (320a-320c) of the plant and transmit the control information to a third computer terminal via a first communication network; a second computer terminal configured to cause the change content for changing the setting condition of the facility (320a-320c) arranged in the plant represented by the control information to be applied to the facility (320a-320c); and the third computer terminal configured to further add a second signature to the control information and transmit the control information to the second computer terminal via the first communication network when the first signature added to the control information is a correct signature and the control information represents the change content for changing the setting condition of the facility (320a-320c) arranged in the plant applicable to the facility (320a-320c), wherein each of the first computer terminal, the second computer terminal and the third computer terminal are connected to the first communication network, wherein the second computer terminal and the facility (320a-320c) are connected by a second communication network, wherein the first computer terminal is configured to receive the change content for the facility (320a-320c), add the first signature to the change information representing the received change content, and transmit the change information, wherein the third computer terminal is configured to further add the second signature to the change information and transmit the change information when the first signature added to the change information is a correct signature and the change information represents the change content applicable to the facility (320a-320c), wherein the second computer terminal is configured to cause the change content represented by the change information to be applied to the facility (320a-320c) of the plant, wherein the first communication network is a communication network in which a block chain is constructed, and wherein the second communication network is a dedicated communication circuit.