A probe that is inserted into a body cavity, wherein an inner unit (inner assembly) comprises an oscillator unit, an intermediate substrate, an electronic circuit substrate, and a backing member. An exhaust heat sheet is joined to an area at the perimeter of the rear surface of the electronic circuit substrate. The exhaust heat sheet comprises a main body part and a plurality of wings that extend to the outside from the main body part. The plurality of wings include a right wing and a left wing. The wings are inserted into two slits formed in a probe head case (heat radiating shell), and the end parts of the wings are accommodated in and adhered to two recessed sections formed in the outer surface of the probe head case. Thus, heat generated inside the probe head case can be directly transferred to the outer surface of the probe head case.