PURPOSE: To wash many kinds of objects to be washed on the same line by arranging washing tanks having ultrasonic vibrators fixed thereto in two or more rows along the feed line of the objects to be washed and providing a plurality of washing tanks in the direction crossing the feed line at a right angle in a freely movable manner.

CONSTITUTION: Washing tanks having ultrasonic vibrators fixed thereto, for example, a pickling soln. washing tank 51, an alkali washing soln. washing tank 61 and a shower rinse washing tank 7 are provided along the feed line of an object to be washed and, further, a plurality of washing tanks, for example, the pickling soln. washing tank 51 and an alkali washing soln. washing tank 52, the alkali washing soln. washing tank 61 and a pickling soln. washing tank 62 as well as the shower rinse washing tank 71 and a tap water washing tank 72 are provided in the direction crossing the feed line at a right angle so as to be freely movable by screw rods 29. A plurality of the washing tanks are moved in the direction crossing the feed line at a right angle and positioned along the feed line to wash the object to be washed on the same line.