This invention is directed to an output correction system for an analog sensor which outputs an analog signal corresponding to a quantity of state. The output correction system for the analog sensor comprises a control section which receives an output from the analog sensor obtained under condition where the quantity of state is zero and an output from the analog sensor obtained under pseudo-condition equivalent to a certain quantity of state; a first arithmetic section for calculating a gradient on the basis of the output under the zero condition and the output under the pseudo-condition; a storage section for storing output characteristics defined by said gradient; and a second arithmetic section for calculating a quantity of state corresponding to the output from the analog sensor on the basis of the output characteristics defined by the gradient.