A serial communication apparatus for a Local Interconnect Network (LIN), comprising: an input terminal (Tin) that receives an input signal; an output circuit (21; 22; 23) that drives a load (RL) connected to an output terminal (Tout); a slew rate control circuit that generates a drive signal for driving the output circuit based on the input signal, and controls a slew rate of the drive signal; a noise detection circuit (31; 34) that detects noise superimposed on an output signal line which is coupled to the output terminal (Tout), and generates a noise detection signal in response to a detection result, the noise detection circuit being coupled to the output terminal (Tout); and a switching circuit that switches an impedance of the slew rate control circuit based on the noise detection signal, wherein the noise detection circuit includes: a first capacitance (C31), one end of which is connected to the output terminal (Tout); a second capacitance (C32), one end of which is coupled to a second power supply terminal; and a rectifier (D1) coupled between the first capacitance (C31) and the second capacitance (C32), the noise detection signal is generated based on a voltage of a joint of the rectifier (D1) and the second capacitance (C32), and the switching circuit switches the impedance of the slew rate control circuit , so that the impedance becomes smaller as compared with a case where the noise detection signal is not activated, when the noise detection circuit detects the noise and the noise detection signal is activated. an input terminal (Tin) that receives an input signal; an output circuit (21; 22; 23) that drives a load (RL) connected to an output terminal (Tout); a slew rate control circuit that generates a drive signal for driving the output circuit based on the input signal, and controls a slew rate of the drive signal; a noise detection circuit (31; 34) that detects noise superimposed on an output signal line which is coupled to the output terminal (Tout), and generates a noise detection signal in response to a detection result, the noise detection circuit being coupled to the output terminal (Tout); and a switching circuit that switches an impedance of the slew rate control circuit based on the noise detection signal, wherein the noise detection circuit includes: a first capacitance (C31), one end of which is connected to the output terminal (Tout); a second capacitance (C32), one end of which is coupled to a second power supply terminal; and a rectifier (D1) coupled between the first capacitance (C31) and the second capacitance (C32), a first capacitance (C31), one end of which is connected to the output terminal (Tout); a second capacitance (C32), one end of which is coupled to a second power supply terminal; and a rectifier (D1) coupled between the first capacitance (C31) and the second capacitance (C32), the noise detection signal is generated based on a voltage of a joint of the rectifier (D1) and the second capacitance (C32), and the switching circuit switches the impedance of the slew rate control circuit , so that the impedance becomes smaller as compared with a case where the noise detection signal is not activated, when the noise detection circuit detects the noise and the noise detection signal is activated. <EOS>