PURPOSE: To improve washing efficiency and to minimize the amt. of the water to be drained by injecting a washing liquid to a work in the washing liquid to wash the work, washing away the detergent in pure water in a prerinsing section, rinsing the work in rinsing sections, and providing circulating means and regenerating means for the pure water in the prerinsing section.

CONSTITUTION: The work W is transported by using a carrier 2 and is washed. The washing liquid is first injected to the work to wash the work in the washing section 3. The work is then immersed into the pure water and is vertically oscillated to wash away the washing liquid, etc., in 1st and 2nd prerinsing sections 4, 5. The pure water in the 1st and 2nd prerinsing sections 4, 5 is circulated while the water is regenerated by respective filter units 413, 513. The pure water is injected to the work in the pure water in the 1st rinsing section 6. The work is immersed into the pure water and is vertically oscillated to wash away the washing water, etc., in the 2nd rinsing section. Finally, the pure water remaining in the high-temp. atmosphere of a drying section 8 is removed.