An ultrasonic endoscope comprising an insertion portion comprising a distal hard portion which has: an endoscopic observation unit; and an ultrasonic observation unit fitted on an outer circumferential section of the endoscopic observation unit, wherein: the ultrasonic observation unit comprises: an ultrasonic transducer array having ultrasonic transducers, and a backing layer cylindrically formed on an inner circumferential surface of the ultrasonic transducer array; and a flexible circuit board on which formed are first terminals each connected to an electrode of a respective one of the ultrasonic transducers, second terminals to which cables are respectively connected, and wiring patterns respectively formed between the first and second terminals, wherein the flexible circuit board has a stepped structure having a large-diameter section on which the first terminals are formed and a small-diameter section on which the second terminals are formed, and an annular support section is formed on an inner circumferential side of the small-diameter section.