A disk device comprises a case for supporting the entire disk device, a base chassis on which a spindle motor for rotating the disk is set, a counterweight for absorbing vibration of the base chassis, and a plurality of elastic bodies for mutually supporting the case, the base chassis and the counterweight. The rotating body includes a receiving member for receiving fluid discharged from the nozzle for flushing when the non-holding region faces the nozzle and a removing member for removing the fluid, received by the receiving member, from the receiving member. In the cooling device, both outside air introduction port and outside air discharge port are provided in an outer side plate of the casing, and a drain space is provided between the heat exchanger and the outer side plate of the casing so that outside air passages communicate with the outside air discharge port through the drain space. A concentration gradient of the \u03b1-alumina in the edge portion decreases in a first direction from the edge portion to the main portion.