To surely prevent a broken disk chip from flying out and to achieve dust prevention in a state that a tray is housed, by a simple and inexpensive structure not impeding a thinned size to be obtained, in a disk unit and an electronic apparatus incorporated with the same.

A disk opening 6 is closed without a gap to achieve both a broken disk chip fly-out prevention function and a dust prevention function by a double structure in which an extended part 5b is integrally formed at the front end 5a of the tray 5 and an upper frame body 3a is integrally formed at the tray opening 6 of a body frame 3. Thus, the extended part 5b and the upper frame body 3a are formed so as to be overlaid back and forth when the tray 5 is carried into a unit case 2.