A body fat measurement device includes a bioelectrical impedance measurement body attachment unit with an electrode support and a belt. The belt includes a stretchable region at one part. The electrode support includes a fixing portion fixed with one end of the belt, and a holder for holding a portion closer to another end of the belt in a movable manner and including a wrapping length adjustment mechanism for adjusting the wrapping length thereof. The body fat measurement device includes a displacement amount detection unit for detecting a displacement amount of the belt caused by the stretching of the stretchable region, and a wrapping length adjustment mechanism control section for controlling the wrapping length adjustment mechanism based on information detected by the displacement amount detection unit. According to such a configuration, there is obtained a body fat measurement device including a bioelectrical impedance measurement abdomen attachment unit enabling smooth breathing motion without hardly giving pain to the subject, and capable of being closely attached with satisfactory reproducibility regardless of a waist length of the subject.