Driving force transmission mechanism and image forming apparatus

A driving force transmission mechanism that transmits a driving force in one direction, the driving force transmission mechanism comprising

• a first transmission member and a second transmission member that are arranged on an identical rotational center axis, wherein
• the first transmission member includes a transmission claw engaged with the second transmission member, the transmission claw includes, at a position away from the rotational center axis, a fixing portion of the first transmission member, and extends in a direction crossing a direction directed from the fixing portion to the rotational center axis, and
• the second transmission member includes a stopper engaged with a tip end of the transmission claw and one or more holding portions engaged with a side of the transmission claw, which faces the rotational center axis, wherein
• the holding portion includes a holding groove that is recessed from a position where the holding portion is engaged with the transmission claw to a side of the rotational center axis.