A metal nanoparticle material for molecular sensing, that includes a metal nanoparticle aggregate including three to ten metal nanoparticles connected to each other through an organic molecule so that adjacent metal nanoparticles are bonded and spaced apart a predetermined distance, the aggregate containing a Raman active molecule within a field applied to the aggregate, wherein the metal nanoparticle material emits enhanced Raman scattering light from the Raman active molecule in an enhanced electric field; a method for producing the metal nanoparticle material for molecular sensing; and a molecular sensing method using the metal nanoparticle material for molecular sensing.