Image forming apparatus and damper

An image forming-apparatus, comprising:

• an image forming device to form an image on a sheet;
• a first shaft provided in the image forming device;
• an upper unit to rotate about the first shaft with respect to the image forming device;
• a slide portion provided on the upper unit to slide reciprocally in a forward direction toward a side of the image forming device in which the first shaft is provided and a backward direction opposite to the forward direction, the forward direction and the backward direction being perpendicular to an axial direction of the first shaft;
• a force applier to apply a force to the upper unit in an open direction, in which the upper unit is opened with respect to the image forming device;
• and
• a force adjuster to decrease the force applied by the force applier to the upper unit as the slide portion slides with respect to the upper unit in the forward direction.