A vehicle tray having an open-prevention mechanism may include a rotating member integrally connected to a tray cover and rotatably coupled to the tray to support the tray cover, and an inertia detecting member pivotally coupled to the tray, a portion of the inertia detecting member being selectively engaged with a stopper portion of the rotating member according to an impact to prevent rotation of the rotating member when the impact greater than a predetermined level is applied to the tray.