PROBLEM TO BE SOLVED: To reduce false recognition of being a guest other than a registered user more.SOLUTION: Whether a measurer is a registered user or a guest is determined according to whether measured weight and the amount of increase or decrease of biological impedance (BI) with respect to weight and the BI as user information on the registered user are respectively within an allowable range. When the measurer is not determined to be the registered user, redetermination processing is performed after changing the allowable range. About the allowable range used in the redetermination processing, the allowable range of weight is made wider and the allowable range of the biological impedance is narrower than the allowable range used in the first measurer determination. Even in the case where significant weight change exists, wherein the measurer is not determined to be the registered user by a reference allowable range used in the first measurer determination processing in this way, significantly increased or decreased weight can be made within an identification allowable range by expanding the allowable value of weight change in measurer determination processing again, using the fact that the value of the biological impedance does not change so much.
