To provide a fallen snow sliding-down device for preventing a snowfall from becoming fallen snow due to the deterioration of a surface of a roofing material even in a roof having a structure using a smooth material for the roofing material of the roof to prevent snow from sticking to the roof by increasing a gradient of a gable roof.

Respective members have two sealed bag-like bodies 1 and 2 having a supply exhaust port of air, and formed of a film of a flexible material. These two sealed bag-like bodies are constituted so as to be mutually connected by a straight line part 3 possessed by the respective members, and are installed so that a connecting part comes to the ridge of the gable roof.