PURPOSE: To form a coated film, uniform and of superior appearance, on a material to be coated by carrying immersion coating while the coating liquid in an immersion tank including insertion of the material to be coated and drawing-up processes is retained at a specific liquid level all the time and providing a piston-type movable bottom plate and a driving means for lifting up and lowering the movable bottom plate.

CONSTITUTION: A material 8 to be coated is retained on a support rod 9, inserted into an immersion tank 1 from above and immersed in coating liquid 5. In the immersion process, a hydraulic cylinder is so operated as to absorb discharged liquid amount of coating liquid due to the immersion of the material 8 to be coated in the liquid and retain the given liquid level H, and a movable bottom plate 2 is lowered from the level L1 in the stand-by state down to the level L2 by operating a hydaulic cylinder 4. For that purpose, the liquid level of coating liquid 5 is monitored by a liquid level sensor 7, and the hydraulic cylinder is controlled base on the sensing signal of the sensor and the movable bottom plate 2 is lowered by controlling the hydraulic cylinder 4. Successively a handling device supporting the material 8 to be coated is turned over, and the material 8 to be coated is drawn up from the immersion tank 1. In the drawing-up process, the hydraulic cylinder 4 is so controlled as to retain the liquid level of the coating liquid 5 to the given level H in the process of drawing up the material 8 to be coated completely above the liquid level. The coating work can be carried out while keeping the coating liquid at a specific level all the time by the arrangement.