The present disclosure provides an industrial control apparatus that minimizes the increase in time taken for detecting a short-circuit in the apparatus and the decrease in the number of unoccupied terminals of a microcomputer due to detection of a short-circuit event. The industrial control apparatus includes first and second voltage supplying units, first and second circuits, an amplification command circuit, and a voltage amplifier incorporated into the first circuit. The amplification command circuit compares the input signal from the first circuit with that of the second signal, and if the comparison results in agreement, outputs to the voltage amplifier an amplification command signal indicating an amplification factor that allows a pre-amplified signal inputted to the voltage amplifier after being amplified to have a voltage out of the range of detecting connection or non-connection of the first input device to the first circuit.