An ultrasonic endoscope comprising an insertion portion including a distal hard portion. The insertion portion comprises an ultrasonic transducer arranged in the distal hard portion and a treatment equipment lead-out hole, a slant surface on which an endoscopic viewing section is formed, the slant surface being provided in a position rear of the treatment equipment lead-out hole and a balloon removably arranged in a fit area on the ultrasonic transducer. The distal hard portion comprises a balloon-fit groove between an arrangement region of the ultrasonic transducer and an opening of the treatment equipment lead-out hole. The balloon has an end including a retaining ring that fits in the balloon-fit groove. The distal hard portion further comprises a treatment equipment guide member that slidably guides the treatment equipment across an arrangement area of the balloon-fit groove and up to a position on a beginning side of a scanning range of the ultrasonic transducer.