Abstract: A biosensor capable of highly sensitive detection of a recognition target substance while having structural stability is provided at low cost. The biosensor is for capturing and detecting a recognition target substance and includes a linker made of a hydrocarbon compound having two or more particular functional groups, a peptide serving as a molecular recognition substance directly bonded to one particular functional group of the linker, and a support directly bonded to the other particular functional group of the linker. Preferably, the particular functional groups each are a reaction product functional group of an epoxy group and an amino group. The peptide is an artificially synthesized peptide including three or more consecutive amino acid sequences, among amino acid sequences of a natural immunoglobulin, that exist in a part corresponding to a hypervariable area of the natural immunoglobulin.