A device includes a body weight obtainment unit for obtaining measurement data； a storage unit for storing the measurement data； a target calculation unit that, based on the measurement data in, calculates a target diurnal fluctuation amount including a body weight fluctuation amount during sleep and a body weight diurnal target increase/decrease amount； and a computation unit that, based on the target diurnal fluctuation amount, calculates a target value to serve as a target when measuring a pre-sleep body weight value at a second timing before the measurement subject sleeps relative to a post-waking body weight value that is measured at a first timing after the measurement subject wakes. The target calculation unit calculates the diurnal target increase/decrease amount based on the measurement data in the storage unit so that the diurnal target increase/decrease amount is within a predetermined increase/decrease percentage range of the post-waking body weight value.
