To provide an ultrasonic endoscope whose forefront is capable of conducting puncture procedures, or the like, while observing equally favorable optical and ultrasonic tomographic images.

The forefront of the ultrasonic endoscope in which the ultrasonic probe 2 for scanning ultrasonic signals to be sent and received in addition to an observing window 3 housing an objective optical system 10 of a forward cross-eyed type for optically observing an ultrasonic scanning region and a protruded outlet of a processing tool, namely an outlet of a channel for the processing tool to be inserted through, is arranged nearby the rear side of the ultrasonic probe 2, wherein a non-roof prism that reflects the light reflected at the first reflecting surface 11a after entering from a plane of incidence toward a direction of an optical axis at the rear of the incident plane 11b as a prism 11 that changes a direction of an optical axis 10x in the forefront of the objective optical system 11 is arranged.