PURPOSE: To adjust an image density by a simple constitution by providing a roller in the vicinity of the surface of an image carrying body, in a position after forming a toner image by liquid developer, and also varying an interval between the surface of the image carrying body and the roller.

CONSTITUTION: A projecting part 7b is formed on an arm 7 for supporting an electrode roller 4, and this projecting part 7b and a plunger 9 are connected operatively. When this plunger 9 is energized, the arm 7 turns counterclockwise against action of a spring 8, and can vary an interval (d) between a photosensitive body 1 and the electrode roller 4. In this way, an image forming luminous flux itself is not controlled, and an adhesion quantity of developer is controlled at a development time point, therefore, an image density can be adjusted by a simple constitution.