PROBLEM TO BE SOLVED: To simplify manufacturing and handling and to make it possible to use a coating apparatus at various assembling position. SOLUTION: An outlet opening 8 facing to a roller 2 of a printing machine and a medium-amount adjusting roller 11 supported rotatably on the outlet opening are provided in a container 1 which can be filled with a medium and the range projected from the outlet opening 8 can be pushed on the roller 2 and a quantity adjusting gap 23 with a controllable width is provided between the outer peripheral face of the quantity adjusting roller 11 and the restricted face positioned by facing to the quantity adjusting roller 11 and the quantity adjusting roller 11 is freely rotatably supported and can be driven by means of a roller 2 based on frictional contact with the roller 2 and the position of the quantity adjusting roller 11 is changeable to the container 1 through an adjusting device 22 in the radial direction to the axial line of rotation and the width of the quantity adjusting gap relates to the position of the quantity adjusting roller 11 in the container 1.