A rotary kiln comprises a rotary drum having a large number of lifters along its inner wall. The end portion of each lifter which is extended interiorly of the rotary drum is bent in the rotational direction of the rotary drum. To the end of each lifter are attached a number of chain like fittings which makes sliding movements along the inner wall surface of the rotary drum and along the upper and lower faces of each lifter in accordance with the rotation of the rotary drum. The chain like fittings so act as to prevent a substance to be dried from adhering to the inner wall of the rotary drum and to the lifters through making sliding movements in accordance with the drum rotation. Further, since the chain like fittings act to break the substance into small pieces and to release it upon dropping due to their own weights, it is dried effectively.