Provided is a pest control device with which it is possible to reliably exterminate pests in a cultivation room. This invention is provided with a spraying means equipped with nozzles for spraying a chemical solution containing a pest control agent into a plant cultivation room. Liquid droplets being sprayed from the nozzles measure 100 μm or smaller, and have an average particle diameter of 10-30 μm. The nozzles are disposed so that the spray from the nozzles fills the entirety of the plant cultivation room interior in a uniform manner. The invention is provided with a control device for causing the nozzles to spray so that the humidity in the plant cultivation room is 90-100%.