The deceleration rate of a detection member is set such that, even if the ultrasonic wave sending and receiving unit is driven at full stroke, the total number of rotations of the detection member is set to be no more than a single rotation, and the initial driving position of the ultrasonic wave sending and receiving unit is determined by accurately detecting the origin position, which is a reference when controlling swinging of the ultrasonic wave sending and receiving unit. This ultrasonic probe is internally provided with an ultrasonic wave sending and receiving unit (100), and is also provided with a housing (21) in which an ultrasonic wave propagation liquid (22) is sealed, a drive device which transmits rotational drive force of a drive motor (1) to swing the aforementioned ultrasonic wave sending and receiving unit (100), and a detection device which detects the origin position, which is the reference when controlling swinging of the aforementioned ultrasonic wave sending and receiving unit (100)； this ultrasonic probe is characterized in that the detection device removes rotation from an intermediary member through which the detection device transmits rotational drive force, slows the rotation and transmits the same to the detection member (14) of the detection device, and detects the origin (O) position by detecting rotation of the detection member (14) with a sensor (13).La vitesse de décélération d'un élément de détection est réglée de telle sorte que, même si l'unité d'envoi et de réception d'onde ultrasonore est entraînée à pleine course, le nombre total de rotations de l'élément de détection est réglé pour ne pas être supérieur à une seule rotation, et la position d'entraînement initiale de l'unité d'envoi et de réception d'onde ultrasonore est déterminée par détection précise de la position d'origine, qui est une référence lors de la commande d'oscillation de l'unité d'envoi et de réception d'onde ultrasonore. Cette sonde ultrasonore comprend, à l'in
