The present invention provides a disk device with enhanced heat radiation effects which aims at effectively suppressing heat generation from a circuit substrate without preventing slimming of a disk device, facilitating assemblies and adjustments in manufacturing steps, and simplifying maintenance/repair work. In the present invention, connectors 18C to be connected to flat cables 18B are intensively disposed close to one edge of a circuit substrate 6, the circuit substrate 6 is fixed between side wall sections 7B, 7B, and a ventilation path for air produced by rotation of a disk 2 is formed by a space enclosed by the circuit substrate 6 and side wall sections 7B. Electronic parts 18 mounted on the circuit substrate 6 are fixed to a frame 7 oriented toward the disk 2 so as to face this ventilation path. This allows the air produced through rotation of the disk 2 to pass through a ventilation path 28 and go out of the frame 7 and allows heat from the electronic parts 18 to radiate outward. At the same time, by removing the circuit substrate 6 with the flat cable 18B connected thereto, it is possible to uncover the upside of the frame 7 and facilitate assembly and adjustment in manufacturing steps.