PROBLEM TO BE SOLVED: To provide a device for surely measuring weight of a load.SOLUTION: There is provided a load mode for measuring weight (mass) of a load. When the load mode is selected by an operation of an operation key, during a predetermined period or a period until a predetermined operation is performed, the operation key is invalided. After the operation key is invalided by selection of the load mode, when measurement is finished and the load is unloaded from a living matter information measurement device, the operation key is validated. Therefore, when using the living matter information measurement device for measuring weight of the load, such a situation in which, the load contacts the operation key therefore measurement must be performed again, or the load has to be mounted on a position avoiding the operation key, can be prevented.SELECTED DRAWING: Figure 6
