A device for locking the porthole door of a washing machine and similar appliances is provided with an opening (5) for the passage of a hook mounted on the porthole door. The device comprises a slider (7) cooperating with the end of the door hook and an electromechanical delaying device (20) electrically connected to the operating controls of the washing machine and adapted to block said slider (7) through a slider stopper. The contact terminal for applying a voltage to a thermistor of the delaying device (20) is formed by two metal strips (28, 29) the ends of which project from the housing of said delaying device (20), with the blades positioned one in front of the other in correspondence of a conductive member (11) fastened to said slider (7) and adapted to close the circuit when the porthole door is closed. |