A self width-adjusting device holder comprises two width-adjustable side walls or plates, a stopper a resilient width-adjustment mechanism and a base plate. The two width-adjustable side plates are adapted to be pushed away from each other when a device is inserted and to automatically move toward each another or retract when a device is removed from the holder. The width-adjustable plates may be slidably mounted on the base plate. As these two side plates slide, the receiving area may be adjusted to be adapted to the devices with different sizes.