PURPOSE: To provide a pressure ultrasonic washing device wherein the pressure device pressurizing the washing soln. in an ultrasonic washing tank is hardly damaged.

CONSTITUTION: A washing soln. sealing means 10 is provided to an ultrasonic washing tank 1 consisting of a tank main body 4 and a freely openable and closable lid body 6 and a pressure means pressurizing the washing soln. 3 in the ultrasonic washing tank 1 is provided. The pressure means consists of the liquid conduits 8, 15 connecting the washing soln. sealing tank 10 and the ultrasonic washing tank 1 and washing soln. circulating means 32, 8 circulating the washing soln. 3 in the ultrasonic washing tank 1. The pressure device 18 introduces compressed gas into the hermetically closed container simultaneously with the pressurization of the washing soln. 3 in the washing soln. sealing tank 10 to internally pressurize the hermetically closed container 2. A pressure introducing liquid sealing tank is provided and the liquid pressure introducing conduit connected to the hermetically sealed container is provided and the pressure device 18 pressurizes not only the washing soln. 3 in the washing soln. sealing tank 10 but also the liquid received in the pressure introducing liquid sealing tank and pressure force is transmitted to the hermetically closed container 2 through a liquid pressure introducing conduit.