An image forming apparatus including a photosensitive member, an optical scanning device including a transmission member configured to cause laser light for scanning the photosensitive member to pass through the transmission member, and a developing device configured to develop an electrostatic latent image with toner, the electrostatic latent image being scanned by the laser light and formed on the photosensitive member; a cleaning mechanism configured to clean the transmission member; a counter configured to store a count value that is a number of sheets on which an image forming operation is performed, and a control unit which executes a cleaning sequence before execution of an adjustment sequence, and resets the count value upon execution of the cleaning sequence, in a case where the count value is less than or equal to a predetermined value.