A backing material is provided on the back face side of a piezoelectric transducer, with a first width substantially equal to the piezoelectric transducer widthwise and perpendicular to the radiation direction. A front face of a layer located on the front face side with regard to a wiring pattern has a width substantially equal to the first width. Moreover, the back face of this layer has a second width shorter than the first width. A space is provided between this layer and the backing material due to the difference between the first width and the second width of this layer, and a covering member covering the wiring pattern covers the wiring pattern extending at least from the folded section of the flexible substrate into the space.