To provide a method and an apparatus for treating waste such as a hydroxide and a metal oxide which efficiently dry/solidify the waste by making good use of sunlight thereby realize inexpensive treatment of the waste such as the hydroxide and the metal oxide discharged when ground water is treated, enable the volume of the waste to be discharged to be reduced as much as possible and facilitate the post treatment of the waste to be discharged.

The waste S such as the hydroxide and the metal oxide discharged when ground water is treated is dried/solidified by supplying the waste S to a sun-drying/filtering bed A having a water-permeable bottom and four water-permeable peripheral walls to dehydrate the waste S by permeating water through the bottom and the four peripheral walls and dry the dehydrated waste S by sunlight and using a moisture discharging rod 13 for sucking water by a capillary phenomenon and vaporizing or discharging the sucked water to the outside in combination with the sun drying/filtering bed.