Abstract: A substrate for immobilizing biomolecules comprises a chip substrate, a hydrophilic monolayer, and a lipid bilayer, and a biochip comprising the substrate for immobilizing biomolecules on which biomolecules are immobilized. The substrate for immobilizing biomolecules includes a transparent chip substrate, a metal layer provided on the chip substrate, a monolayer provided on the metal layer, and a lipid bilayer provided on the monolayer. The metal layer is composed of fine particles of Au, the monolayer is composed of self-assembled molecules represented by X—(CH2)n—OH (where X is a thiol group), and the lipid bilayer is composed of self-assembled phospholipids. The monolayer and the lipid bilayer are relatively flexibly bound together via hydrogen bonds. In the biochip, a receptor is immobilized on the lipid bilayer via a biorecognition molecule.