An operational amplifier circuit includes a potential control circuit connected between a current sense semiconductor element connected in parallel with a main semiconductor element and a current detection resistor. The potential control circuit controls an output potential of the current sense semiconductor element to be equal to that of the main semiconductor element. The potential control circuit includes a current control element controlling an output current of the current sense semiconductor element and an operational amplifier outputting a signal corresponding to an output potential difference between the current sense semiconductor element and the main semiconductor element to the current control element. An input offset voltage polarity determination unit determines a polarity of an input offset voltage of the operational amplifier according to the output potential difference. The polarity of the input offset voltage is controlled to be constant based on polarity determination of the input offset voltage.