A CPU (170) of a human subject index estimation apparatus (1) computes a waist circumference based on body weight measured by a weight scale (110) and bioelectric impedance measured by a bioelectric impedance measurement unit (200A), and information such as age and height which was input through input unit (150). The computed waist circumference is stored, along with the information such as age and height, in a third storage unit (140) that is a rewritable non-volatile memory. The CPU (170) displays the waist circumference on display unit (160).