PROBLEM TO BE SOLVED: To provide a sugar compound fixed semiconductor sensing device capable of detecting a biological substance with high sensitivity under physiological conditions, and to provide a method for detecting a biological substance using the device.SOLUTION: A first organic monomolecular film formed of a monomolecular film of alkoxysilane having an aminooxy alkyl group having 3 to 22 carbon atoms is formed on the first insulating layer of a field-effect transistor which is constituted by forming the first insulating layer containing a silicon oxide or an inorganic oxide on a semiconductor as a reaction gate insulating section, and a sugar compound is bonded directly to the organic monomolecular film through the aminooxy alkyl group to constitute the sugar compound fixed semiconductor sensing device having a sugar compound/organic monomolecular film/insulating layer/semiconductor structure as a detection section.
