An endoscope apparatus 2 according to the present invention includes an insertion portion 9 having a distal end portion 6 and at least two channels 54 and 63; an optical observation system 51 provided on one surface of the distal end portion so as to face an axial direction different from a direction of an insertion axis X of the insertion portion; a first channel opening 41a provided on one surface of the distal end portion near the optical observation system; an ultrasound transducer array 61 provided on the one surface of the distal end portion and having a scanning surface Z parallel to the insertion axis; and a second channel opening 41b provided on a proximal end side of the ultrasound transducer array.
