PROBLEM TO BE SOLVED: To provide an insect repellent injection device which is not equipped with a pump, and does not require routing of an electric wire, in which an installation work of a device is easy and inexpensive, maintenance of the device is easy, and which is capable of acquiring sufficient insect repellent injection pressure.SOLUTION: An insect repellent injection device includes a cylinder 3, a discharge port 5 disposed on the front end surface of the cylinder, valve means 6 for opening/closing the discharge port, a piston 4 accommodated in the cylinder, a rod 7 attached to the piston that projects from the rear end part of the cylinder, spring means 13 for energizing the piston to an advancing direction, an insect repellent supply port 18 attached to the front end part of the cylinder, valve means 15 capable of opening/closing the insect repellent supply port, and an attached case 33 communicated with the discharge port through a tube that is attached to a building frame of a wooden building, for
