Abstract: The present invention relates to a biosensor including: a bottom plate having a base film having a lead mounted at one side of the top surface thereof, an electrode member formed on the base film, a spacer formed on the top surface of the electrode member so as to secure a recess having a predetermined width formed on the electrode member, and an enzyme reaction layer formed transversely on the top surface of the electrode member in such a fashion as to be positioned in the recess of the spacer; and a top plate formed integrally with the bottom plate and having the same configuration as the bottom plate.