The new type of amperometric biosensor described herein, which was fabricated by using a track-etched microporous membrane electrode for glucose detection, comprises a prereactor electrode, a detector electrode, and an immobilized enzyme reactor sandwiched between these electrodes. Because the sample solution flows through this system, the interferents are electrolyzed completely at the prereactor, positioned upstream of the enzyme reactor. The increased current response at the detector electrode derives solely from oxidation of hydrogen peroxide produced in the enzymatic reaction. Sensitive and selective response toward glucose detection was obtained with no other catalytic material such as peroxidase or an electron mediator.