To provide a space diffusion method of a pest repellent capable of effectively diffusing the pest repellent, letting a gas phase concentration in space reach effective concentration exhibiting repellent effect in short time, and maintaining the effective concentration for long time.SOLUTION: A space diffusion method of a pest repellent includes a process for attaching an air blower equipment type pest repellent sheet 1 by holding an aqueous composition for pest repellency containing a following component (A) of 0.1 mass% to 20 mass% of 68 mass% to 750 mass% based on mass of a substrate sheet to a blower 2 without contact with a rotating blade 4 of the blower 2 at a state that flow of air to front of the blower 2 is not blocked, and a process for operating the blower 2 in the chamber. (A) There is provided the pest repellent having vapor pressure at 25°C of 0.00006 Pa to 210 Pa.SELECTED DRAWING: Figure 2【課題】害虫忌避剤を効率的に拡散させることができ、空間内の気相濃度を忌避効果を発揮する有効濃度に短時間に到達させ得るとともに、その有効濃度を長時間維持させることができる害虫忌避剤の空間拡散方法を提供すること。【解決手段】本発明の害虫忌避剤の空間拡散方法は、下記の成分（Ａ）を０．１質量％以上２０質量％以下含む害虫忌避用水性組成物を、基材シートの質量に対して６８質量％以上７５０質量％以下保持させた送風機装着型害虫忌避シート１を、送風機２の回転する羽根４と接触せず、かつ、送風機２の前方への空気の流れを妨げない状態に送風機２に取り付ける工程と、該送風機２を室内で運転する工程とを含む。（Ａ）２５℃における蒸気圧が０．００００６Ｐａ～２１０Ｐａである害虫忌避剤。【選択図】図２
