An image forming apparatus comprising: an image bearer configured to bear a latent image; a first driver configured to rotate the image bearer; a developing device configured to contain developer, the developing device including a developing roller configured to develop the latent image on a surface of the image bearer; a second driver configured to rotate the developing roller; and a controller configured to control the first driver and the second driver and set a linear speed ratio representing a ratio of a linear speed of the developing roller relative to a linear speed of the image bearer at a position where the developing roller faces the image bearer, wherein the controller is configured to execute a first driving in an idle time, during which image formation is not performed, the first driving in which the developing roller rotates with rotation of the image bearer stopped, characterised in that the controller is further configured to: execute a second driving in the idle time, for a predetermined period subsequent to the first driving, in which both the developing roller and the image bearer rotate, drive the developing roller and the image bearer such that, at a position where the developing roller and the image bearer face each other, the surfaces of the two rollers move in the same tangential direction during the second driving and in image formation, and set the linear speed ratio to a first ratio smaller than 1 in the second driving and to a second ratio equal to or greater than 1 in image formation. an image bearer configured to bear a latent image; a first driver configured to rotate the image bearer; a developing device configured to contain developer, the developing device including a developing roller configured to develop the latent image on a surface of the image bearer; a second driver configured to rotate the developing roller; and a controller configured to control the first driver and the second driver and set a linear speed ratio representing a ratio of a linear speed of the developing roller relative to a linear speed of the image bearer at a position where the developing roller faces the image bearer, wherein the controller is configured to execute a first driving in an idle time, during which image formation is not performed, the first driving in which the developing roller rotates with rotation of the image bearer stopped, characterised in that the controller is further configured to: execute a second driving in the idle time, for a predetermined period subsequent to the first driving, in which both the developing roller and the image bearer rotate, drive the developing roller and the image bearer such that, at a position where the developing roller and the image bearer face each other, the surfaces of the two rollers move in the same tangential direction during the second driving and in image formation, and set the linear speed ratio to a first ratio smaller than 1 in the second driving and to a second ratio equal to or greater than 1 in image formation. execute a second driving in the idle time, for a predetermined period subsequent to the first driving, in which both the developing roller and the image bearer rotate, drive the developing roller and the image bearer such that, at a position where the developing roller and the image bearer face each other, the surfaces of the two rollers move in the same tangential direction during the second driving and in image formation, and set the linear speed ratio to a first ratio smaller than 1 in the second driving and to a second ratio equal to or greater than 1 in image formation.