A semiconductor integrated circuit comprising: a first transmission circuit generating and outputting a first transmission signal reflecting a first data signal supplied from outside; a first reception circuit reproducing the first data signal based on a first reception signal; a first isolation element isolating the first transmission circuit from the first reception circuit and transmitting the first transmission signal as the first reception signal; an abnormality detection part detecting an abnormality that can cause a malfunction in signal transmission via the first isolation element, and a control part which, upon detection of an abnormality by the abnormality detection part, outputs a stop signal regardless of the first data signal supplied from outside to the first transmission circuit; a gate driver outputting a gate control signal based on the first data signal reproduced by the first reception circuit, the gate control signal being used to control on/off operations of an output transistor for controlling a current flowing through a load; wherein the first transmission circuit is mounted over a first semiconductor chip driven by a first power source between a first source voltage and a first ground voltage, wherein the first reception circuit is mounted over a second semiconductor chip driven by a second power source between a second source voltage and a second ground voltage, wherein the abnormality detection part and the control part are mounted over the second semiconductor chip along with the first reception circuit or mounted over the first semiconductor chip along with the first transmission circuit, wherein, upon detection of an abnormality by the abnormality detection part, the control part turns off the output transistor by outputting the stop signal, and wherein the abnormality detection part includes a common mode noise detection circuit detecting the abnormality if common mode noise attributable to the voltage difference between the first ground voltage and the second ground voltage exceeds a predetermined threshold range. a first transmission circuit generating and outputting a first transmission signal reflecting a first data signal supplied from outside; a first reception circuit reproducing the first data signal based on a first reception signal; a first isolation element isolating the first transmission circuit from the first reception circuit and transmitting the first transmission signal as the first reception signal; an abnormality detection part detecting an abnormality that can cause a malfunction in signal transmission via the first isolation element, and a control part which, upon detection of an abnormality by the abnormality detection part, outputs a stop signal regardless of the first data signal supplied from outside to the first transmission circuit; a gate driver outputting a gate control signal based on the first data signal reproduced by the first reception circuit, the gate control signal being used to control on/off operations of an output transistor for controlling a current flowing through a load; wherein the first transmission circuit is mounted over a first semiconductor chip driven by a first power source between a first source voltage and a first ground voltage, wherein the first reception circuit is mounted over a second semiconductor chip driven by a second power source between a second source voltage and a second ground voltage, wherein the abnormality detection part and the control part are mounted over the second semiconductor chip along with the first reception circuit or mounted over the first semiconductor chip along with the first transmission circuit, wherein, upon detection of an abnormality by the abnormality detection part, the control part turns off the output transistor by outputting the stop signal, and wherein the abnormality detection part includes a common mode noise detection circuit detecting the abnormality if common mode noise attributable to the voltage difference between the first ground voltage and the second ground voltage exceeds a predetermined threshold range.