An optical sample detection system comprising: a sensor chip including: a dielectric member; having an upper surface, a first surface forming an incidence surface and a second side surface forming an emission surface; a metal film adjacent to the upper surface of the dielectric member; a reaction layer adjacent to an upper surface of the metal film; and a lid member disposed on an upper surface of the reaction layer; the lid member being translucent with respect to the excitation light and fluorescence; a chip loading portion including a chip holding unit for holding the sensor chip; and a light projecting unit adapted to emit the excitation light toward the incidence surface to irradiate the metal film with the excitation light through the dielectric member, the optical sample detection system being adapted to detect a sample by irradiating the metal film with the excitation light through the dielectric member, wherein the lid member has a larger width than the width of the dielectric member in an optical path cross section of the excitation light, wherein the optical sample detection system additionally comprises a light receiving unit disposed above the sensor chip, wherein part of the excitation light reflected by the metal film is reflected by the emission surface to form emission surface reflected light, characterized in that the dielectric member is further configured such that the emission surface reflected light is reflected towards the bottom surface, and that the emission surface reflected light is emitted to an outside of the dielectric member such that it is not incident on the lid member within a measurement scanning angle of the excitation light, wherein a bottom surface of the dielectric member is a scattering surface, and wherein the measurement scanning angle means an emission angle of the emitted excitation light obtained by scanning the light projecting unit while the light projecting unit emits the excitation light and the light receiving unit measures the fluorescence and/or scattered light. a dielectric member; having an upper surface, a first surface forming an incidence surface and a second side surface forming an emission surface; a metal film adjacent to the upper surface of the dielectric member; a reaction layer adjacent to an upper surface of the metal film; and a lid member disposed on an upper surface of the reaction layer; the lid member being translucent with respect to the excitation light and fluorescence; a chip loading portion including a chip holding unit for holding the sensor chip; and a light projecting unit adapted to emit the excitation light toward the incidence surface to irradiate the metal film with the excitation light through the dielectric member, the optical sample detection system being adapted to detect a sample by irradiating the metal film with the excitation light through the dielectric member, wherein the lid member has a larger width than the width of the dielectric member in an optical path cross section of the excitation light, wherein the optical sample detection system additionally comprises a light receiving unit disposed above the sensor chip, wherein part of the excitation light reflected by the metal film is reflected by the emission surface to form emission surface reflected light, characterized in that the dielectric member is further configured such that the emission surface reflected light is reflected towards the bottom surface, and that the emission surface reflected light is emitted to an outside of the dielectric member such that it is not incident on the lid member within a measurement scanning angle of the excitation light, wherein a bottom surface of the dielectric member is a scattering surface, and wherein the measurement scanning angle means an emission angle of the emitted excitation light obtained by scanning the light projecting unit while the light projecting unit emits the excitation light and the light receiving unit measures the fluorescence and/or scattered light.