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