[OBJECT] To provide a device for removing radioactive cesium from waste material containing radioactive cesium, doing so at low energy and in a dependable manner. [MEANS OF REALIZING THE OBJECT] The removal device 1 for radioactive cesium is provided with: a rotary kiln 41 which is provided with a burner 41b supplying from the kiln outlet an organic matter 03 contaminated with radioactive cesium, and an inorganic matter charging port 41a supplying from the kiln inlet inorganic matter S4 contaminated with radioactive cesium, and which is employed to burn the organic matter 03 together with the inorganic matter S4; and a recovery device cooling tower 51, a cyclone 52, a bag filter 53 for recovering cesium that has volatilized in the rotary kiln. A drying/crushing device (dryer 21, crusher 22) for drying and crushing the organic matter O1 prior to charging the radioactive cesium-contaminated organic matter to the rotary kiln can be provided. Additionally, a reforming/drying/crushing device (reformer 31, dryer 32, crusher 23) for reforming, drying, and crushing the inorganic matter S1 can be provided. During burning of the organic matter 03 together with the inorganic matter S4, a calcium source can be added as a reaction accelerant A to the rotary kiln.