PURPOSE: To detoxify a large amt. of marine products having fear containing cadmium without using an expensive plant to treat them as ash, for example, for landfilling.

CONSTITUTION: Marine products containing cadmium are dried (2) in a drying oven and, for example, a heavy metal insolubilizing treatment agent such as a chelating agent is added to the dried marine products to insolubilize cadmium contained in marine products (5).