An endoscope apparatus 1 includes a transparent member 32 that is provided at a distal end of an insertion portion 11 of an endoscope 2 and opposed to an image pickup optical system 34, a transducer 37 that is attached to an inner surface of the transparent member 32, a diffraction grating 40 that is provided on an outer surface of the transparent member, and converts an ultrasound vibration f from the transducer 37 into a surface acoustic wave φ which propagates on the outer surface of the transparent member 32, and absorption portions 32a, 38 that are provided at an outer peripheral portion of the transparent member 32, and deflect the propagated surface acoustic wave φ to a surface different from the outer surface to absorb the surface acoustic wave.
