In an ultrasonic transducer comprising a first electrode, a first insulating film disposed on the first electrode, a hollow part provided above the first insulating film and disposed between surfaces above and below the hollow part, a second insulating film disposed above the hollow part, and a second electrode disposed on the second insulating film, a first conductive film disposed on the side of the surface below the hollow part and a second conductive film disposed on the side of the surface above the hollow part are provided, the first conductive film and the second conductive film are disposed so that they overlap with a region in which the surfaces above and below the hollow part contact with each other as seen from above when the transducer is driven, and they do not overlap with each other in the region as seen from above. With such a configuration, there are provided a structure suitable for, even when the surface above the hollow part contacts with the surface below the hollow part, suppressing concentration of electric fields and electric currents in the insulating films in the contact region, and suppressing injection of electrical charge into the insulating films and degradation of dielectric strength thereof, and an ultrasonic diagnostic device using it.
