PURPOSE: To obtain a filter for sulfides which permits an increase in the volume of the gases to be treated in one hour per apparent volume of adsorbents, is easy to regenerated and can be molded into a cartridge type by depositing active ferrite powder directly on fibers.

CONSTITUTION: A ferrous sulfate soln. and a ferric chloride soln. are mixed at a 1:2 ratio, and this soln. is neutralized with an NaOH soln., whereby active ferrite of fine powder having no water of crystallization is obtd. The fine powder 2 of active ferrite is deposited by arbitrary methods on fibers 1 such as paper, synthetic fibers, glass, asbestos, or the like, whereby a filter element is produced. In use, the element is worked to a wave- or star-shaped filter and this filter is incorporated into a desulfurizer. The surfaces of the fine powder of the active ferrite which is an adsorbent is utilized entirely and the increase in an SV value are made possible. This filter is easy to regenerate by repetition of washing and drying followed by air oxidation.