A gas sensor system of a gas sensor control device connected to a gas sensor, including a gas sensing element composed of a solid electrolyte body ( 11, 12) and a pair of electrodes formed on the solid electrolyte body ( 11, 12), in which an element current occurs depending on a concentration of a specified component in measuring gases upon receipt of a voltage applied across the pair of electrodes, the gas sensor control device comprising: a current-voltage converter consisted of a resistor having one terminal connected to one of the pair of electrodes for measuring the element current flowing therethrough; an output circuit connected to the one terminal for outputting a measured result in response to the element current, measured with the current-voltage converter, as an element current measured value; an applied voltage setting circuit connected to the other terminal of the current-voltage converter, which is configured to set an applied voltage (Vcc) to be applied across the pair of electrodes of the sensing element; a first electric pathway connected between the output circuit and the applied voltage setting circuit to apply the element current measured value thereto; a second electric pathway, connected between the one terminal of the current-voltage converter and the applied voltage setting circuit, in which no element current flows; first switch means provided in the first electric pathway for selectively opening and closing the first electric pathway in response to a circuit switching signal; second switch means provided in the second electric pathway for selectively opening and closing the second electric pathway in response to an inverted signal of the circuit switching signal; and calculating means for calculating the concentration of the specified component based on the element current measured value output from the output circuit in the presence of the voltage applied from the applied voltage setting circuit; wherein, when the circuit switching signal for causing an open state of the first electric pathway and for causing a closed state of the second electric pathway is issued, the applied voltage setting circuit is configured to set the applied voltage (Vss) at a regulated level such that a potential difference between both terminals of the current-voltage converter lies at zero. a current-voltage converter consisted of a resistor having one terminal connected to one of the pair of electrodes for measuring the element current flowing therethrough; an output circuit connected to the one terminal for outputting a measured result in response to the element current, measured with the current-voltage converter, as an element current measured value; an applied voltage setting circuit connected to the other terminal of the current-voltage converter, which is configured to set an applied voltage (Vcc) to be applied across the pair of electrodes of the sensing element; a first electric pathway connected between the output circuit and the applied voltage setting circuit to apply the element current measured value thereto; a second electric pathway, connected between the one terminal of the current-voltage converter and the applied voltage setting circuit, in which no element current flows; first switch means provided in the first electric pathway for selectively opening and closing the first electric pathway in response to a circuit switching signal; second switch means provided in the second electric pathway for selectively opening and closing the second electric pathway in response to an inverted signal of the circuit switching signal; and calculating means for calculating the concentration of the specified component based on the element current measured value output from the output circuit in the presence of the voltage applied from the applied voltage setting circuit; wherein, when the circuit switching signal for causing an open state of the first electric pathway and for causing a closed state of the second electric pathway is issued, the applied voltage setting circuit is configured to set the applied voltage (Vss) at a regulated level such that a potential difference between both terminals of the current-voltage converter lies at zero.