Roller driving apparatus used in image forming apparatus

A roller driving apparatus used in an image forming apparatus, the roller driving apparatus comprising:

• a roller having a shaft and configured to be rotatably driven;
• and
• a gear fixed to a first end portion of the shaft in a longitudinal direction of the roller,
• wherein the gear includes:
• when viewed along the longitudinal direction,
• a hole into which the first end portion of the shaft is inserted and formed of an inner peripheral surface including an inner circumferential surface centering on a first center;
• a projection, in a case where two areas divided by a virtual line passing through the first center are a first area and a second area, disposed in the first area and projecting in a direction toward the first center relative to the inner peripheral surface;
• and
• a gear portion disposed so that a pitch circle is provided outside the hole in a radial direction centering on the first center,
• wherein the first end portion of the shaft is inserted into the hole of the gear in a press-fit state by at least a part of the projection of the gear being deformed, and
• wherein, when viewed along the longitudinal direction, a second center, which is a center of the pitch circle, is disposed in the second area.