Fuel tank cap locking device

A fuel tank cap locking device comprising:

• a cap that is configured to open and close a fuel filler port leading to a fuel tank of a vehicle by moving between a closed position where the fuel filler port is closed, and an open position where the fuel filler port is opened;
• an operation unit that is configured to be allowed to perform a swing operation around a swing shaft by an operator;
• an engagement unit that is movable in conjunction with the swing operation of the operation unit, and that is configured to operate between an engagement position where a state in which the cap closes the fuel filler port is held, and an allowable position where engagement is released and an opening operation of the cap is allowed;
• and
• a lock unit that is configured to lock movement of the engagement unit from the engagement position to the allowable position, or release a lock to allow the movement of the engagement unit from the engagement position to the allowable position,
• a slider that is configured to interlock with the engagement unit;
• a detection switch that is configured to detect movement of the slider,
• wherein the lock is released by the lock unit on condition that the detection switch detects the movement of the slider, and
• wherein the lock unit includes a lock member that is movable between an interference position where the lock member interferes with an interfered portion formed at a predetermined position of the engagement unit and locks, and a non-interference position where the lock member does not interfere with the interfered portion and the lock is released when the engagement unit moves from the engagement position to the allowable position by the swing operation of the operation unit.