Sheet feeding device and image forming apparatus

A sheet feeding device comprising:

• a holding unit configured to hold a stack of sheets;
• a pickup roller disposed in contact with a sheet placed on top of the stack held in the holding unit, the pickup roller being configured to rotate and feed the sheet from the stack;
• a holder arm having a distal end to which the pickup roller is attached, wherein the holder arm has a swing center set at a position closer, in a stack direction of the stack, to the pickup roller side than the holding unit, and the distal end of the holder arm extends from the swing center to the holding unit side;
• and
• a resiliently-deformable unit, which generates a swing moment to swing the holder arm in a direction which increases contact surface pressure between the sheet held in the holding unit and the pickup roller,
• wherein the swing moment increases as a contact angle increases,
• wherein the contact angle is an angle between an extension direction of the holder arm and the sheet held in the holding unit.