To prevent the falling of a door panel when the tension of a wire is extinguished while reducing the manufacturing cost.

This device has a blade plate 6 arranged on the side of a door panel 1A on the lower end and supported in such a manner as to be rockable within a prescribed range toward the outside of an opening part, and a locking member 8 arranged in a position opposed to the blade plate 6 and having a protruding part 80 vertically protruded toward the blade plate 6 at a prescribed intervals. It also has a collar 61 arranged on the blade plate 6 and making contact with a wire 11, an inclined part 6B formed on the blade plate 6 so as to be opposed to the collar 61 with a rocking shaft 60 between and capable of engaging with the protruding part 80, and a spring for energizing the blade plate 6 so that the inclined part 6B is turned to the locking member 8.