Apparatus 1 for evaluating catalyst performance according to the invention comprises a reaction vessel 2 in which a plurality of catalysts S are disposed at a distance, supply pipes 3 for supplying a reactant gas into the reaction vessel 2, a plurality of measuring instruments 7 provided with gas sensors 71 for sensing the gas formed by the contact of the reactant gas with a plurality of catalysts S, and outputting signals according to the kinds and concentrations of the formed gas, and a calculating unit 8 for receiving the output signals from the plurality of measuring instruments 7 and identifying the kinds of the formed gas and calculating the concentrations thereof. With such a constitution, performance evaluation on a plurality of catalysts can be made concurrently, quick and in simple steps.