The depuration method for shellfish comprises preparing seawater that is purified by irradiation with ultraviolet rays and made to contain oxygen gas bubbles in a storage unit, maintaining while bringing the seawater into contact with the shellfish, and deriving the seawater from the storage unit, in which the bubbles have superfine bubbles with a diameter of less than 100 nm, and the superfine bubbles selectively adsorb and desorb viruses accumulated in the shellfish. The depuration system for shellfish comprises a purification unit for purifying seawater with ultraviolet rays, a superfine bubble generating unit for generating oxygen gas bubbles with a diameter of less than 100 nm in the seawater, and a storage unit for storing the seawater, that is connected to the purification unit for purifying seawater with ultraviolet rays and the superfine bubble generating unit, in which the storage unit retains shellfish.
