A tray door attachment structure for a disk device has a tray door and a torsion coil spring. The tray door is pivotably attached to a front panel of the disk device. The tray door includes a door body, a door arm on which a spring receiving portion and a spring supporting portion located adjacent to the spring receiving portion are formed and a rotational axle formed on the door arm and attached to the front panel. The torsion coil spring biases the tray door in a closing direction. The torsion spring includes a coil attached to the rotational axle, a first arm abutting the front panel and a second arm abutting the spring receiving portion. The second arm has a distal end portion. The distal end portion is supported by the tray door and is latched by the spring supporting portion.