Disclosed herein is an aptamer sensor including a substrate having metal nanoparticles formed thereon, an aptamer attached to surfaces of the metal nanoparticles to form a structure by selectively reacting with a target material to be detected, and an intercalating agent inserted between the aptamer and the target material in reaction of the aptamer with the target material to increase shift of an absorption spectrum due to local surface plasmon resonance sensor through aggregation toward the metal nanoparticles.