To simplify the constitution of a submerged polishing device polishing a workpiece in polishing liquid, miniaturize it, and increase the economical property by constituting the polishing device into a compact liquid tank structure.

A liquid tank 1 storing polishing liquid 2 is formed like a circular ring, and the liquid tank 1 is attached to a lower surface plate 4 like a circular ring so as to surround inner and outer peripheries of the lower surface plate 4. The inside of the liquid tank 1 is partitioned into an annular inner liquid chamber 1b positioned on an inner peripheral side of the lower surface plate 4 and an annular outer liquid chamber 1a positioned on an outer peripheral side of the lower surface plate 4. A liquid supply nozzle 14 for supplying polishing liquid is arranged in the inner liquid chamber 1b, and a liquid discharge port 15 is provided in the outer liquid chamber 1a.