Disclosed is a spray type ultrasonic washing apparatus using a coaxial nozzle structure which is composed of inner and outer hollow frustums for supplying deaerated washing liquid in the annular passage delimited by the outer and inner frustums and supplying nondeaerated washing liquid in the inner frustum, thus permitting deaerated washing liquid to be enclosed by nondeaerated washing liquid in spraying against work to be washed, thereby isolating deaerated washing liquid from the surrounding atmosphere to prevent invasion of air into the deaerated washing liquid. Thus, cavitation can be formed effectively in the deaerated washing liquid, and washing can be performed at an increased efficiency.