A body weight management device includes a measurement unit that measures a body impedance of a measurement subject, an impedance change detection unit that detects a temporal change in the measured body impedance, a variation amount computation unit that computes a body impedance variation amount in a unit period, and a determination unit that makes determination about a trend for subsequent changes in the measurement subjects body weight, using the body impedance variation in the unit period, and an output unit that outputs a result of the determination.