An ultrasonic transducer according to the present invention includes: two or more ultrasonic transducer cells, each of which has a lower electrode, a first insulating layer placed on the lower electrode, a cavity placed on the first insulating layer, a second insulating layer placed on the cavity, and an upper electrode placed above the second insulating layer; channels which communicate the cavities with each other; the second insulating layer placed on the channels; holes formed in the second insulating layer placed on the channels; and sealing portions which seal the holes, where that part of the sealing portions which enters the channels is the same in cross-sectional shape as the holes.