A technique that provides: an ultrasonic transducer in which the accurate arrangement of piezoelectric elements and the electric conductive state between electrode layers are reserved; and an ultrasonic diagnosis apparatus and an ultrasonic flaw inspection apparatus which use the ultrasonic transducer is provided. According to the technique, a plurality of piezoelectric elements 1, each being a stacked body in which predetermined numbers of piezoelectric layers 2 and electrode layers 3 are alternately stacked and although this has both sides that are substantially flat along a stacking direction, side electrodes 6 to connect the predetermined electrode layers 3 are placed outside both of the sides, are arranged in a direction orthogonal to the stacking direction, wherein an interval holding member 10 having a predetermined thickness is put between the sides on which the side electrodes 6 of the piezoelectric elements 1 adjacent to each other are formed.