A leak determining apparatus for an evaporated fuel treatment system is provided for executing a leak determination for an evaporated fuel treatment system without suspending it even in such a condition that variations in fuel could occur, thereby accurately providing a leak determination result. When a residual charging degree of the battery becomes equal to or lower than a charging-starting target value, an electrical generator is driven by a vehicle engine so that the battery is charged through the electrical generator. The dog tower has a spiral slot opening on one side which enables a dog member to be placed therein and rotated down or up within the dog tower to clamp to the material of the wall or ceiling. Coupled to the general functional control logic, the bank RAS controller includes a rotating shift register having multiple bits. The locking device includes a penetration where a bolt is inserted through the hole.