Disclosed is a pest control agent in the form of a suspension, which exhibits excellent dispersion stability for a long time without forming a hard cake due to settling and separation of solid particles or without losing fluidity due to gelation even when a cationic pest control active ingredient and/or an acid is used. Specifically disclosed is a pest control agent in the form of a suspension, which contains (a) a cationic pest control active ingredient and/or an acid, (b) a nonionic thickening agent, (c) a nonionic surface active agent, (d) a solid active ingredient and (e) water.
