Abstract: A safe-deposit box uses a lock using a tongue, a first mechanical device, a second mechanical device, an electromagnetic valve, a control unit and a keypad. A renter's key drives the first mechanical device from a first position to a second position for actuating the control unit. The electromagnetic valve is in a first position for retaining the first mechanical device in the second position. A code is input through the keypad to the control unit for driving the electromagnetic valve from the first position to a second position for allowing movement of the mechanical device from the second position to a third position for retracting the tongue. A clerk's key can drive the second mechanical device from a first position to a second position for driving the electromagnetic valve from the first position to the second position and turning off the control unit.