To provide a method of treating a waste formed material such as slate containing the asbestos to finally dispose of or easily recycle it by stabilizing the asbestos fibers without scattering them.

(1) The waste formed material containing asbestos is crushed in a liquid containing a silicone resin emulsified liquid, scooped from the liquid and after compression molded, heated and fired to be disposed of. (2) The fired material is crushed again to be mixed with cement and formed/solidified to be used. (3) To increase the strength of the fired material in the (1), ash obtained by firing plants, particularly ash containing 15% total potassium is added to the scooped crushed chips.