To prevent invasion of a pigeon, or the like, by closing a curtain by discrimating rain, wind, a man, the pigeon, and the like, as it is unsanitary and troublesome when the pigeon comes into a veranda, or the like, of a multiple family dwelling and makes a nest, drops feces, and so forth.

A device for preventing invasion of and shutting out harmful birds and insects discriminates the rain, the wind, the man, the pigeon, and the like, with various sensors such as a camera 3, a rain sensitive sensor 9, an auditory sensor by catching movements of them and selects whether it is harmful or not. A net is usually open. When the sensors detect the pigeon, the pigeon is prevented from invading by closing the net 5.