Provided are a blood pressure measuring apparatus capable of effectively eliminating the influence which the volume change in an upstream portion of an occluding cuff has on a pulse wave detection cuff in an oscillometric double-cuff system, increasing the S/N ratio of systolic blood pressure detection, and accurately measuring the blood pressure with an inexpensive arrangement, a cuff, and a blood pressure measuring method. The apparatus includes a first pipe (106) connected to an occluding air bag (108) and sub air bag (109). The first pipe is connected to the sub air bag, and the sub air bag is connected to the occluding air bag via an entirely foldable rod shape member (111) capable of maintaining a hollow portion. The sub air bag is laid over the occluding air bag by folding a middle pipe.