PURPOSE: To provide the device for applying a color developer which can apply a large amt. of the color developer.

CONSTITUTION: A tungsten wire 24 is tensed to face a conductor roller 20 and a brush roller 21 with which a brush scraping blade 26 comes into contact together with the color developer 28 is disposed in a color developer case 25 below this wire. The color developer 28 is deposited on the brush by rotation of the brush roller 21. The brush near the blade 26 springs up the color developer 28 by its elasticity and supplies the color developer to the spacing between the tungsten wire 24 and a base P when the brush is scraped by the blade 26. A negative high voltage is held impressed to the tungsten wire 24 and, therefore, the color developer particles supplied in this space are charged by the impingement of a negative ion shower and is driven toward the conductive roller 20 by receiving the effect of powerful Coulomb force, by which the particles are deposited in a laminar form on the base P on the conductive roller 20.