A living body information measuring apparatus can suppress the bulge of tendons due to the bending of a wrist or fingers, and has good contact intimacy with arteries, making it possible to make accurate measurements of living body information. A cuff is formed of: a compression fluid bag which is provided for detecting a pulse wave signal, and which can be expanded and contracted by being supplied with a fluid; and two auxiliary fluid bags which are provided on an outer side of the compression fluid bag, and which can be expanded and contracted by being supplied with the fluid. The auxiliary fluid bags have a two-layer structure, and are connected to the compression fluid bag via opening portions, while the auxiliary fluid bags are respectively divided from each other. The compression fluid bag compresses the tendons, the radial artery and the ulnar artery, while the auxiliary fluid bag and the auxiliary fluid bag compress the radial artery and the ulnar artery, respectively. Thus, the bulge of the tendons due to the bending of the wrist and fingers can be suppressed, so that the contact intimacy of the compression fluid bag and the auxiliary fluid bags with the wrist is not hindered