PURPOSE: To obtain a new fuzzy arithmetic circuit with the high responsiveness by providing two operational amplifiers, a comparison signal, a control part, and a function generating circuit and actuating the operational amplifiers only in a linear area of the arithmetic circuit.

CONSTITUTION: When an input signal V1 is inputted to the operational amplifiers OP1 and OP2 respectively, the outputs P1 and P4 of the amplifiers OP1 and OP2 cross the voltage of 0 level at the positions decided by the comparison voltage levels VR and VL respectively. Thus both outputs P1 and P4 rise or fall. These output characteristics are turned into the outputs P2 and P5 having the changed slopes by the regulators VR1 and VR2. The comparators DC1 and DC2 are set at a contact voltage level -VBE and then turned into the outputs P3 and P6 at the negative and positive sides centering on the cross positions decided by the comparison voltage levels VR and VL respectively. At a function generating part FG, the outputs P3, P6 and P7 are inputted to the bases of transistors 5 - 7 respectively and synthesized. Thus the trapezoidal output characteristic VOUT is obtained. Therefore a fuzzy arithmetic circuit using the amplifiers OP1 and OP2 can maintain high speed responsiveness.