An electrophotographic image forming apparatus for forming an image on a recording medium in a state in which a cartridge is mounted to an apparatus main body, the apparatus comprising: a drive source; a drive gear configured to be rotated by the drive source; and a driving-force transmission member configured to be rotated by a driving force transmitted from the drive gear to transmit the driving force to the cartridge, characterised in that, the driving-force transmission member comprises: a coupling portion configured to engage with a cartridge coupling disposed at a longitudinal end of a first rotating member of the cartridge and transmit the driving force to the cartridge coupling so as to rotate the first rotating member; a first helical gear portion configured to engage with a driven gear disposed at a longitudinal end of a second rotating member of the cartridge to transmit the driving force so as to rotate the second rotating member; and a second helical gear portion configured to engage with the drive gear to receive the driving force, wherein the coupling portion, the first helical gear portion, and the second helical gear portion rotate integrally with each other when the driving-force transmission member rotates about an axis of rotation of the driving-force transmission member that is parallel to an axis of rotation of the first rotating member, and when the driving-force transmission member is at an engaging position where the coupling portion engages with the cartridge coupling and the driving-force transmission member is rotated by the driving force transmitted from the drive gear, the driving-force transmission member moves toward the cartridge coupling in a direction along the axis of rotation of the first rotating member, wherein, the first helical gear portion receives a force from the driven gear for moving the driving-force transmission member in the direction toward a predetermined positioning portion, the second helical gear portion receives a force from the drive gear for moving the driving-force transmission member in the direction toward the predetermined positioning portion, and the coupling portion receives a force from the cartridge coupling for moving the driving-force transmission member in the direction toward the predetermined positioning portion, and wherein the forces for moving the driving-force transmission member cause the driving-force transmission member to come into contact with the predetermined positioning portion at the engaging position. a drive source; a drive gear configured to be rotated by the drive source; and a driving-force transmission member configured to be rotated by a driving force transmitted from the drive gear to transmit the driving force to the cartridge, characterised in that, the driving-force transmission member comprises: a coupling portion configured to engage with a cartridge coupling disposed at a longitudinal end of a first rotating member of the cartridge and transmit the driving force to the cartridge coupling so as to rotate the first rotating member; a first helical gear portion configured to engage with a driven gear disposed at a longitudinal end of a second rotating member of the cartridge to transmit the driving force so as to rotate the second rotating member; and a second helical gear portion configured to engage with the drive gear to receive the driving force, a coupling portion configured to engage with a cartridge coupling disposed at a longitudinal end of a first rotating member of the cartridge and transmit the driving force to the cartridge coupling so as to rotate the first rotating member; a first helical gear portion configured to engage with a driven gear disposed at a longitudinal end of a second rotating member of the cartridge to transmit the driving force so as to rotate the second rotating member; and a second helical gear portion configured to engage with the drive gear to receive the driving force, wherein the coupling portion, the first helical gear portion, and the second helical gear portion rotate integrally with each other when the driving-force transmission member rotates about an axis of rotation of the driving-force transmission member that is parallel to an axis of rotation of the first rotating member, and when the driving-force transmission member is at an engaging position where the coupling portion engages with the cartridge coupling and the driving-force transmission member is rotated by the driving force transmitted from the drive gear, the driving-force transmission member moves toward the cartridge coupling in a direction along the axis of rotation of the first rotating member, wherein, the first helical gear portion receives a force from the driven gear for moving the driving-force transmission member in the direction toward a predetermined positioning portion, the second helical gear portion receives a force from the drive gear for moving the driving-force transmission member in the direction toward the predetermined positioning portion, and the coupling portion receives a force from the cartridge coupling for moving the driving-force transmission member in the direction toward the predetermined positioning portion, and wherein the forces for moving the driving-force transmission member cause the driving-force transmission member to come into contact with the predetermined positioning portion at the engaging position.