An armrest box comprising a box body, a box cover and a bidirectional opening/closing device, wherein the bidirectional opening/closing device comprises a base, a plate, a trigger mechanism, and two locking mechanisms; wherein each locking mechanism comprises a lock arm with a hinged end and a free end, the lock arm is installed on the base by means of the hinged end, the lock arm and the base are capable of being locked or unlocked, and the lock arm is capable of rotating around the hinged end when the lack arm and the base are unlocked; wherein the two lock arms are arranged symmetrically and in parallel, and the free ends of the two lock arms face opposite directions, such that the two lock arms have opposite directions of rotation; and the trigger mechanism is installed on the plate, and the trigger mechanism is capable of selectively unlock one of the lock arms from the base, such that the lock arm is capable of driving the plate to rotate around the hinged end of the lock arm, wherein each locking mechanism comprises a lock hook, one end of the lock hook is installed in a cavity of the lock arm, and the other end extends out of the lock arm to be matched with a locking part of the base; and the trigger mechanism comprises a trigger lever, the trigger lever is installed on the plate, and the trigger lever is capable of moving in a first direction to extend into the cavity of the lock arm so as to drive the lock hook to be separated from the locking part, characterized in that wherein the trigger lever has a step part, the trigger mechanism comprises a stopping unit, and the stopping unit has a stopping end that is capable of abutting against the step part to limit the trigger lever from moving. each locking mechanism comprises a lock arm with a hinged end and a free end, the lock arm is installed on the base by means of the hinged end, the lock arm and the base are capable of being locked or unlocked, and the lock arm is capable of rotating around the hinged end when the lack arm and the base are unlocked; wherein the two lock arms are arranged symmetrically and in parallel, and the free ends of the two lock arms face opposite directions, such that the two lock arms have opposite directions of rotation; and the trigger mechanism is installed on the plate, and the trigger mechanism is capable of selectively unlock one of the lock arms from the base, such that the lock arm is capable of driving the plate to rotate around the hinged end of the lock arm, wherein each locking mechanism comprises a lock hook, one end of the lock hook is installed in a cavity of the lock arm, and the other end extends out of the lock arm to be matched with a locking part of the base; and the trigger mechanism comprises a trigger lever, the trigger lever is installed on the plate, and the trigger lever is capable of moving in a first direction to extend into the cavity of the lock arm so as to drive the lock hook to be separated from the locking part, characterized in that wherein the trigger lever has a step part, the trigger mechanism comprises a stopping unit, and the stopping unit has a stopping end that is capable of abutting against the step part to limit the trigger lever from moving.