PROBLEM TO BE SOLVED: To prevent an intrusion of insects more reliably in an insect repellent system of a building for preventing the intrusion of insects from an outdoor space to the inside of an entrance room (13) of the building.SOLUTION: In an insect repellent system (10) of a building which includes an entrance room (13) and a first windbreak room (11) provided on an outdoor side of the entrance room (13) for preventing an intrusion of insects from an outdoor space to the inside of the entrance room (13), a room pressure regulating device (20) is provided which regulates each room pressure to make a room pressure on the side of the entrance room (13) of an outside inner door (17) higher than that of the first windbreak room (11) while both an entrance door (16) on an outdoor side of the first windbreak room (11) and the outside inner door (17) on the side of the entrance room (13) are closed.SELECTED DRAWING: Figure 2
