A bioelectrical impedance measurement abdomen attachment unit includes an electrode support for supporting an electrode and a long belt to be wrapped around an abdomen of a subject. The electrode support includes a fixing portion fixed with one end of the belt in a relatively immovable manner with respect to the electrode support, and a holder for holding a portion closer to another end of the belt in a relatively movable manner with respect to the electrode support. The holder includes an attachment portion removably attachable to an arbitrary position of the portion closer to the other end of the belt and a biasing portion for coupling the attachment portion and the electrode support and biasing the attachment portion and the electrode support in an approaching direction. According to such a configuration, there is obtained a bioelectrical impedance measurement attachment unit which enables the electrodes to be pressed against the abdomen of the subject with a constant load with satisfactory reproducibility and which is not painful to the subject.