A lock device adapted for a first object and a second object movable relative to the first object includes a slider, a driving module, a latch and a power module. The driving module can drive the slider to move between a locking position and an unlocking position. The latch is movable relative to the slider. The power module can provide electricity to the driving module. When the second object is located at a retracted position relative to the first object, the driving module can drive the slider to move to the locking position, so that the latch blocks the second object. When the driving module is not driven by the power module, the latch is driven by the second object moving in an opening direction to move from an original state to a non-original state for driving the slider to move from the locking position to the unlocking position.