filter paper composed of short cut pieces of superfine filaments (sff) was developed. it shows high performance, but its hydrodyhamic resistance increases when substrate solution passes through it. a new type of enzyme reactor equipped with knitted sff has been proposed. in this reactor, substrate does not pass through the support but flows along the thin channel and parallel to the support. therefore, it is able to maintain flow rate constant during a considerable period. the productivity of the reactor fairly increases by reducing the thickness of the channel because linear velocity increases with the reduction of the thickness and that contributes to the decrease in mass transfer resistance. 9 refs