This invention provides a blood pressure measuring apparatus capable of stably measuring the blood pressure in even the tragus while suppressing the degree of invasion. An attaching portion (3) of the blood pressure measuring apparatus has an inner cuff (6), an outer cuff (7), and a holding member (10) which holds the inner cuff (6) and outer cuff (7), and the holding member has a “U” shape. The end portions of the holding member (10) where the inner cuff (6) and outer cuff (7) are arranged are almost parallel to each other, and the inner cuff (6) and outer cuff (7) oppose each other. An auxiliary member (80) which comes in contact with a predetermined position of the ear of a person to be measured and increases the attachment stability of the inner cuff (6) and outer cuff (7) at the tragus is attached to the holding member (10).