A semiconductor integrated circuit device comprising: a communication protocol interface serving as an interface of a first communication protocol inputted via a communication bus; a controller controlling an actuator (Ac) based on a message inputted via the communication protocol interface; a first regulator supplying power to the communication protocol interface; and a second regulator supplying and stopping power to the controller and the actuator (Ac) based on a control signal outputted from the communication protocol interface, wherein the communication protocol interface generates the control signal based on a message of a second communication protocol that is different from the first communication protocol transferred from the communication bus (Bc), wherein the communication protocol interface includes a protocol determination unit determining whether the message transferred via the communication bus (Bc) is a message of the first communication protocol or a message of the second communication protocol, and transmitting the message to the controller if the message is the message of the first communication protocol; and an ID determination unit into which the message is inputted when the protocol determination unit determines the message is the message of the second communication protocol, the ID determination unit detecting a recognition number in the message, determining whether the detected recognition number and a recognition number individually allocated to the semiconductor integrated circuit device match, and, if matched, outputting the control signal which operates the second regulator; characterized in that: the semiconductor integrated circuit device further comprises a timer which measures idle time of the controller when a power-source voltage is supplied to the controller, wherein the controller outputs a power-off instruction signal to the ID determination unit when the idle time of the controller of a given time elapses, and the ID determination unit outputs the control signal which stops operation of the second regulator when the power-off instruction signal is received. a communication protocol interface serving as an interface of a first communication protocol inputted via a communication bus; a controller controlling an actuator (Ac) based on a message inputted via the communication protocol interface; a first regulator supplying power to the communication protocol interface; and a second regulator supplying and stopping power to the controller and the actuator (Ac) based on a control signal outputted from the communication protocol interface, wherein the communication protocol interface generates the control signal based on a message of a second communication protocol that is different from the first communication protocol transferred from the communication bus (Bc), wherein the communication protocol interface includes a protocol determination unit determining whether the message transferred via the communication bus (Bc) is a message of the first communication protocol or a message of the second communication protocol, and transmitting the message to the controller if the message is the message of the first communication protocol; and an ID determination unit into which the message is inputted when the protocol determination unit determines the message is the message of the second communication protocol, the ID determination unit detecting a recognition number in the message, determining whether the detected recognition number and a recognition number individually allocated to the semiconductor integrated circuit device match, and, if matched, outputting the control signal which operates the second regulator; characterized in that: the semiconductor integrated circuit device further comprises a timer which measures idle time of the controller when a power-source voltage is supplied to the controller, wherein the controller outputs a power-off instruction signal to the ID determination unit when the idle time of the controller of a given time elapses, and the ID determination unit outputs the control signal which stops operation of the second regulator when the power-off instruction signal is received. the semiconductor integrated circuit device further comprises a timer which measures idle time of the controller when a power-source voltage is supplied to the controller, wherein the controller outputs a power-off instruction signal to the ID determination unit when the idle time of the controller of a given time elapses, and the ID determination unit outputs the control signal which stops operation of the second regulator when the power-off instruction signal is received.