To make it possible to efficiently separate and remove cadmium from the internal organs of fish and shellfishes with relatively small-sized and inexpensive equipment, simultaneously to drastically reduce the volume and weight of the internal organs of the fish and shellfishes to be treated and to utilize the internal organs as fertilizer, feed, fish feed or soil conditions, etc.

The cadmium is removed from a cadmium eluate by immersing the organs of the fish and shellfishes into a strongly acidic liquid to eluate the cadmium into the liquid, then processing these internal organs with a centrifugal separating machine 5 to separate the internal organs to solid residual slag and oil-component as well as the cadmium eluate, adding an alkaline liquid to the cadmium eluate to neutralize the same, then bringing the eluate into contact with an ion exchange resin 13.