An analog to digital converter circuit included in a meter ECU detects an output voltage of a potentiometer and a source voltage outputted from a battery, and converts them to different pieces of digital data. It also detects reference voltages outputted from adjustment resistors and an adjustment battery, and converts them to different pieces of digital data. It then calculates digital data on a corrected sensor output by correcting a detection error associated with a jumper line and a voltage variation in the source voltage based on the digital data.