To provide an electronic control device for a vehicle, which suppresses leakage of a current, flowing out of a communication line of the electronic control device, to a low level when an earth line is broken.

There are provided a diode 11, which blocks current flowing out of an interface circuit 14, and a resistor 12 for current restriction between an interface circuit 14 and an ECU1, whereby the resistor 12 restricts current flowing out of an input-output terminal K when the earth line is broken. On the other hand, the interface circuit 14 draws in current (i.e., low-level-output) when the diode 11 shorts the resistor 12 which allows the interface circuit 14 to draw in output voltage with a sufficiently low value from the input-output terminal K.