A door panel opening and closing device for a casing includes a face panel, a door panel, and a resilient member. The face panel includes a base wall and a first post disposed on the base wall. The door panel includes a pivot arm pivoted to the base wall and having a second post. A pivot juncture between the pivot arm and the base wall is defined as a turning axis. The door panel is turnable about the turning axis between closed and open positions. The resilient member is an extension spring having two ends hooked to the first and second posts, respectively. When the door panel is turned from the closed position past a specific angular position, the door panel will automatically spring to the open position by virtue of a directional change of a component of tension force of the resilient member to an outward direction.