A cleaning device of an image forming machine including a pair of arm members each having one end portion pivotable about a support shaft, a cleaning roller rotatably supported between front end portions of the arm members via a shaft, helical compression springs for urging the arm members so as to bring the cleaning roller into contact under pressure with the surface of a photoconductor drum, a drive gear of the photoconductor drum, and a driven gear of the cleaning roller in mesh with the drive gear. Each of the arm members is disposed axially outwardly of the photoconductor drum. The center of the support shaft of each of the arm members is either placed on an extension of a line of action passing the point of engagement between the drive gear and the driven gear, or placed on an extension of a straight line passing the point of engagement, the straight line being within an angular range of some angle to the line of action.