A LIN receiver includes a voltage divider that divides an input voltage and outputs the divided voltage, and a peak hold circuit that outputs a peak voltage of the input voltage. The LIN receiver is configured to generate a threshold voltage to be used for determining a voltage signal of a communication bus. The threshold voltage is generated from a voltage signal of the communication bus such that the peak value of the voltage signal (i.e., equivalent to a battery voltage) is held by the peak hold circuit and divided by the voltage divider. Although the communication bus is connected to an on-vehicle battery of which voltage varies with time, by using the voltage signal of the communication bus, a 5V system ECU can generate a threshold voltage which varies responding to the variation of the battery voltage. Hence, the voltage signal can be determined correctly as either high or low level.