A light detecting device comprising: a plurality of detection regions configured to accommodate a sample that is capable of emitting fluorescence light, a plurality of light reflecting sections configured to reflect at least a portion of the fluorescence light emitted from the sample in a direction toward a light detector; and a light transmission controlling section for blocking at least a portion of excitation light that is directed to the sample from a light source from scattering in the direction toward the light detector, the light transmission controlling section being in form of a layer that prevents excitation light from scattering in the direction of the light detector, wherein the light transmission controlling section is in a position where the fluorescence light is directed from the detection region and transmits fluorescence light emitted from the sample, wherein each light reflecting section reflects at least a portion of the fluorescence light emitted from a plurality of samples associated with a plurality of the detection regions in the direction toward the light detector, characterized in that a plurality of condenser lenses for excitation light are placed, respectively, between the light source and a respective light detection region, and the light transmission controlling section is positioned between the detection regions and the light reflecting sections such that the light transmission controlling section and the light reflecting sections are arranged on the same side of the detection regions and opposite to the side of the light source, and in that the detection regions, the light reflection regions and the light transmission controlling section form part of a light detecting chip. a plurality of detection regions configured to accommodate a sample that is capable of emitting fluorescence light, a plurality of light reflecting sections configured to reflect at least a portion of the fluorescence light emitted from the sample in a direction toward a light detector; and a light transmission controlling section for blocking at least a portion of excitation light that is directed to the sample from a light source from scattering in the direction toward the light detector, the light transmission controlling section being in form of a layer that prevents excitation light from scattering in the direction of the light detector, wherein the light transmission controlling section is in a position where the fluorescence light is directed from the detection region and transmits fluorescence light emitted from the sample, wherein each light reflecting section reflects at least a portion of the fluorescence light emitted from a plurality of samples associated with a plurality of the detection regions in the direction toward the light detector, characterized in that a plurality of condenser lenses for excitation light are placed, respectively, between the light source and a respective light detection region, and the light transmission controlling section is positioned between the detection regions and the light reflecting sections such that the light transmission controlling section and the light reflecting sections are arranged on the same side of the detection regions and opposite to the side of the light source, and in that the detection regions, the light reflection regions and the light transmission controlling section form part of a light detecting chip.