Inside the body of an image forming device, first to fifth electric charge providers are mounted in a first location out of a path of an air flow to the suction unit caused by the action of the suction unit, and a sixth electric charge provider is mounted in a second location through which external air flows in the body caused by the action of the suction unit. Each electric charge provider emits charges in ambient air to cause ultrafine particles floating in the ambient air to clump together.