A body composition management apparatus for a pregnant woman which measures body fat or body water by a bioelectrical impedance method is provided. The apparatus comprises: first input means, second input means, measurement means, first computation means, and second computation means, wherein the first input means inputs personal data of a pregnant woman such as a body height and a body weight, the second input means inputs the gestational weeks, the measurement means measures the bioelectrical impedance of the pregnant woman, the first computation means computes a body fat mass or a total body water from the personal data and the impedance, and the second computation means computes a body fat mass or total body water in a non-pregnant state from the computed body fat mass or total body water and the amount of an increase in body weight from the non-pregnant state.