An object of the present invention is to shorten time required for detecting disconnection in an input terminal of an A/D conversion circuit. A semiconductor device includes a first input channel that couples a first input terminal and an A/D conversion unit to each other, a second input channel that couples a second input terminal and the A/D conversion unit to each other, and a control circuit unit that separates the second input channel from the second input terminal and the A/D conversion unit to charge or discharge the second input channel when a signal input into the first input terminal is sampled by the A/D conversion unit.