A refrigerator comprising: a storage room that is divided into sections by a heat insulation wall and a heat insulation door, and configured to store storage items; a plurality of light sources including an internal lighting, that are disposed inside the storage room; a light sensor configured to detect illumination light illuminated from the plurality of light sources; and a calculation control unit configured to perform a calculation process based on a detection result of the light sensor, wherein the calculation control unit includes an attenuation rate calculation unit configured to calculate an attenuation rate from a reference storage room illuminance in a state that the storage items are stored, based on the reference storage room illuminance in a state that the storage items are not stored in the storage room and a detected illuminance by the light sensor, and a storage state estimation unit configured to estimate a storage amount of the storage items, based on a calculation result of the attenuation rate calculation unit, and a door opening and closing detection unit configured to detect opening and closing of the heat insulation door, wherein, in a case where the door opening and closing detection unit detects a closed state, the calculation control unit starts the calculation process, characterized in that the calculation control unit is configured to store relative data associating the attenuation rate of the detected illuminance by the light sensor with the storage amount, based on which the storage amount is estimated, wherein the refrigerator further includes a blue LED (22a, 22b), and the light sensor includes a main light sensor and a sub light sensor, wherein the calculation control unit is configured to function as an attenuation rate calculation correction unit, and wherein the storage state estimation unit is configured to estimate the storage amount of the storage items based on the calculation result of attenuation rate calculation unit and the calculation result of the attenuation rate calculation correction unit, wherein the storage state estimation unit is configured to estimate the storage amount of the storage items using a second lower side surface LED provided on the wall surface on the opposite side of where a first lower side surface LED is provided, and using the sub-light sensor which is disposed in a shifted position on the door side of the same wall surface as where the main light sensor is disposed, wherein the storage state estimation unit is configured to estimate a reflection influence caused by a storage item using the blue LED and the main light sensor, and wherein, in a case where the attenuation rate calculated by the attenuation rate calculation unit is large, the storage state estimation unit estimates that the storage amount is large. a storage room that is divided into sections by a heat insulation wall and a heat insulation door, and configured to store storage items; a plurality of light sources including an internal lighting, that are disposed inside the storage room; a light sensor configured to detect illumination light illuminated from the plurality of light sources; and a calculation control unit configured to perform a calculation process based on a detection result of the light sensor, wherein the calculation control unit includes an attenuation rate calculation unit configured to calculate an attenuation rate from a reference storage room illuminance in a state that the storage items are stored, based on the reference storage room illuminance in a state that the storage items are not stored in the storage room and a detected illuminance by the light sensor, and a storage state estimation unit configured to estimate a storage amount of the storage items, based on a calculation result of the attenuation rate calculation unit, and a door opening and closing detection unit configured to detect opening and closing of the heat insulation door, wherein, in a case where the door opening and closing detection unit detects a closed state, the calculation control unit starts the calculation process, characterized in that the calculation control unit is configured to store relative data associating the attenuation rate of the detected illuminance by the light sensor with the storage amount, based on which the storage amount is estimated, wherein the refrigerator further includes a blue LED (22a, 22b), and the light sensor includes a main light sensor and a sub light sensor, wherein the calculation control unit is configured to function as an attenuation rate calculation correction unit, and wherein the storage state estimation unit is configured to estimate the storage amount of the storage items based on the calculation result of attenuation rate calculation unit and the calculation result of the attenuation rate calculation correction unit, wherein the storage state estimation unit is configured to estimate the storage amount of the storage items using a second lower side surface LED provided on the wall surface on the opposite side of where a first lower side surface LED is provided, and using the sub-light sensor which is disposed in a shifted position on the door side of the same wall surface as where the main light sensor is disposed, wherein the storage state estimation unit is configured to estimate a reflection influence caused by a storage item using the blue LED and the main light sensor, and wherein, in a case where the attenuation rate calculated by the attenuation rate calculation unit is large, the storage state estimation unit estimates that the storage amount is large.