Problem to be SolvedTo provide a processing tank with a simple construction which enables fluidization and agitation of a processing liquid in order to reliably prevent settling of the processing liquid.SolutionAn electrodeposition tank 2 that pools and enables fluidization and agitation of an electrodeposition paint 1 into which a work W is to be immersed, the electrodeposition tank 2 including: a grooved part 7 having a plurality of concave and convex shapes formed along a work-conveying direction on a bottom surface 6 of the electrodeposition tank 2; an electrodeposition paint supply pipe 12 that circulates and supplies the electrodeposition paint 1 to the electrodeposition tank 2; a plurality of branch pipes 13 which are arranged on ridges 10b of the grooved part 7 and which branch off the electrodeposition paint supply pipe 12; and electrodeposition paint discharge nozzles 14 provided oriented upstream in the work-conveying direction at a section of the branch pipes 13 which opposes bottom parts 10a of the grooved part 7.