An adjusting device includes a rotating mechanism disposed between a base and a supporter for adjusting an angle between the supporter and the base, a slide mechanism disposed on the base, and a turntable mechanism slidably disposed on the slide mechanism for holding a panel module, so that the panel module can slide relative to the base along the slide mechanism and for coaxially rotating the panel module relative to the base. A contacting component of the turntable mechanism is for pushing a constraining component of the slide mechanism to pivot relative to an axle, so as to separate the constraining component from a protruding portion of the rotating mechanism for releasing constraint on the supporter relative to the base.