An automatic light measurement device comprising: a group of containers in which two or more reaction containers or two or more reaction containers comprising respective sealing lids are arranged in a matrix form or a column or row form; a measurement mount provided with two or more coupling means that are provided such that they downwardly protrude therefrom, are aligned in a movement path direction, wherein the movement path passes the apertures of the reaction containers, and are suitable for directly joining with respective apertures of said reaction containers by being inserted into the interior of the reaction containers or by fitting to the outer periphery of the respective apertures of the reaction containers or being suitable for indirectly joining with apertures of said reaction containers by fitting to the sealing lids, where the two or more reaction containers comprise respective sealing lids; the two or more coupling means having light guide portions that optically connect with the interior of the respective reaction containers to which they are joined; a mount transfer mechanism configured to move said mount relative to said group of containers in the vertical direction and within the horizontal plane along at least one direction orthogonal to the movement path, a measuring device provided on said mount and having a measuring means having at least one light guide portion that is optically connectable to said light guide portions of said coupling means, that is able to receive light based on an optical state within said reaction containers via said measuring means; a measuring means transfer mechanism arranged on the measurement mount that makes said measuring means movable on said mount along the movement path defined between the two or more coupling means; and a measurement control portion that is configured to control said mount transfer mechanism such that said coupling means are simultaneously directly or indirectly joined with the apertures of said two or more reaction containers or with the sealing lids, and to subsequently control said measuring means transfer mechanism such that said light guide portions of said coupling means and said light guide portion of said measuring means are successively optically connected, and which is configured to instruct a measurement by said measuring device. a group of containers in which two or more reaction containers or two or more reaction containers comprising respective sealing lids are arranged in a matrix form or a column or row form; a measurement mount provided with two or more coupling means that are provided such that they downwardly protrude therefrom, are aligned in a movement path direction, wherein the movement path passes the apertures of the reaction containers, and are suitable for directly joining with respective apertures of said reaction containers by being inserted into the interior of the reaction containers or by fitting to the outer periphery of the respective apertures of the reaction containers or being suitable for indirectly joining with apertures of said reaction containers by fitting to the sealing lids, where the two or more reaction containers comprise respective sealing lids; the two or more coupling means having light guide portions that optically connect with the interior of the respective reaction containers to which they are joined; a mount transfer mechanism configured to move said mount relative to said group of containers in the vertical direction and within the horizontal plane along at least one direction orthogonal to the movement path, a measuring device provided on said mount and having a measuring means having at least one light guide portion that is optically connectable to said light guide portions of said coupling means, that is able to receive light based on an optical state within said reaction containers via said measuring means; a measuring means transfer mechanism arranged on the measurement mount that makes said measuring means movable on said mount along the movement path defined between the two or more coupling means; and a measurement control portion that is configured to control said mount transfer mechanism such that said coupling means are simultaneously directly or indirectly joined with the apertures of said two or more reaction containers or with the sealing lids, and to subsequently control said measuring means transfer mechanism such that said light guide portions of said coupling means and said light guide portion of said measuring means are successively optically connected, and which is configured to instruct a measurement by said measuring device.