Image forming apparatus having circuit board installation in bottom surface

An image forming apparatus, comprising:

• an image forming unit configured to form an image on a sheet;
• a main housing accommodating the image forming unit and having a bottom surface, a first side surface on one side of the image forming unit, and a second side surface on another side of the image forming unit, the main housing comprising:
• a first side cover forming the first side surface;
• and
• a second side cover forming the second side surface, the second side cover opposed to the first side cover in a first direction;
• a sheet tray positioned below the image forming unit and between the first side cover and the second side cover in the first direction, the sheet tray containing a sheet to be fed to the image forming unit;
• and
• a first circuit board removably installed in the main housing,
• wherein the main housing includes an opening in the bottom surface between the first side cover and the sheet tray in the first direction, the opening allowing communication between outside of the main housing and inside of the main housing, and allowing the first circuit board to pass therethrough when the first circuit board is being installed into the main housing.