Provided is a net intrusion prevention device which can prevent an insect-proof net from entering the indoor side of a greenhouse when closing a window, and does not get tired even if the opening and closing of the window is repeated, and is not easily damaged. An opening side rod 3b of a window frame 10 of a window 3 whose one end is swingably attached to a mounting frame 2 attached to a greenhouse, and an opening side rail 2a of the mounting frame 2 facing the opening side rod 3b. In the net intrusion prevention tool 6 for preventing the insect net 4 laid between them from entering the greenhouse, the upper end is attached to the inside of the greenhouse than the insect net 4 of the opening side wall 3b of the window frame 10. The intrusion prevention unit 7 always faces the opening side rail 2a of the mounting frame 2, and the intrusion prevention unit 7 is housed in the greenhouse when the window 3 is closed. [Selection] Figure 2【課題】窓を閉じる際に防虫ネットがビニールハウスの室内側に侵入するのを防止できると共に、窓の開閉を繰り返しても疲労せず、破損しにくいネット侵入防止具を提供する。【解決手段】ビニールハウスに取り付けられる取付枠２に一端が揺動可能に取り付けられる窓３の窓枠１０の開口側框３ｂと開口側框３ｂに対向する取付枠２の開口側桟２ａとの間に架け渡される防虫ネット４の上記ビニールハウス内への侵入を防止するネット侵入防止具６において、上端が窓枠１０の開口側框３ｂの防虫ネット４よりも上記ビニールハウス内側に取り付けられて、常に取付枠２の開口側桟２ａに対向する侵入防止部７を備え、侵入防止部７は、窓３が閉じられると上記ビニールハウス内に収容されることを特徴とする。【選択図】図２
