A sensor comprises a linear region (variable region) in which the output voltage is changed in proportion to the accelerator opening degree, and a stepped region (invariable region) in which the output voltage is not changed with respect to the accelerator opening degree. A resistor electrode for constructing the sensor is formed by laminating a resistor composed of a resistance substance on a base plate in a linear section corresponding to the linear region. In a stepped section corresponding to the stepped region, the resistor electrode is formed by laminating the resistor on a conductive layer composed of a conductive substance formed on the base plate.