Sheet processing device and image forming apparatus

An image forming apparatus comprising:

• an image forming apparatus main body including a sheet storage unit storing a sheet, and a printer unit forming an image on the sheet supplied from the sheet storage unit;
• and
• a sheet processing device performing saddle folding processing on the sheet on which an image is formed, wherein
• the sheet processing device includes:
• a first roller rotatable around a first rotation axis;
• a second roller rotatable around a second rotation axis positioned above the first rotation axis and on a first side of the first rotation axis in a horizontal direction, configured to come into contact with the first roller to form a nip, and configured to convey a saddle-folded booklet obliquely downward by rotating while the booklet is held in the nip;
• and
• a cover covering an outer circumference of the second roller on the first side of the second roller in the horizontal direction and having a lower end part disposed between a first straight line and a second straight line when a straight line including a contact line of the nip is defined as the first straight line, and a straight line parallel to the first straight line and passing through the second rotation axis is defined as the second straight line in a cross section perpendicular to the second rotation axis.