A drive transmission mechanism for transmitting a driving force to a rotated member of an image forming apparatus, the drive transmission mechanism comprising: a drive transmission gear made of resin, including a boss in a shape of a cylinder formed at a center of rotation, a rim formed in a circular shape concentric with the boss outward of the boss in a radial direction and having cogs formed on an outer circumferential surface thereof, and a web coupling the boss with the rim, the drive transmission gear being coupled with a drive input-side gear; and an output-side coupling for outputting a driving force of the drive transmission gear to a driven member (1a to 1d), characterized by a first drive transmission member that is a disk-shaped member made of metal, the first drive transmission member rotating together with the drive transmission gear about a same axis of rotation as the drive transmission gear, a second drive transmission member formed by sintering iron powder, the second drive transmission member transmitting a driving force of the first drive transmission member to the output-side coupling by rotating about a same axis of rotation as the output-side coupling; and a biasing member arranged between the second drive transmission member and the output-side coupling, the biasing member biasing the output-side coupling in a direction away from the second drive transmission member along the axis of rotation, wherein the second drive transmission member has a plurality of engaging portions that engage respectively with a plurality of first engaging holes formed at equal intervals in a circumferential direction in the first drive transmission member with predetermined margins in radial and circumferential directions, and the output-side coupling incline in an arbitrary direction with respect to the axis of rotation of the first drive transmission member, and the driving force from the drive transmission gear is transmitted to an outer circumferential rim of the first drive transmission member. a drive transmission gear made of resin, including a boss in a shape of a cylinder formed at a center of rotation, a rim formed in a circular shape concentric with the boss outward of the boss in a radial direction and having cogs formed on an outer circumferential surface thereof, and a web coupling the boss with the rim, the drive transmission gear being coupled with a drive input-side gear; and an output-side coupling for outputting a driving force of the drive transmission gear to a driven member (1a to 1d), characterized by a first drive transmission member that is a disk-shaped member made of metal, the first drive transmission member rotating together with the drive transmission gear about a same axis of rotation as the drive transmission gear, a second drive transmission member formed by sintering iron powder, the second drive transmission member transmitting a driving force of the first drive transmission member to the output-side coupling by rotating about a same axis of rotation as the output-side coupling; and a biasing member arranged between the second drive transmission member and the output-side coupling, the biasing member biasing the output-side coupling in a direction away from the second drive transmission member along the axis of rotation, wherein the second drive transmission member has a plurality of engaging portions that engage respectively with a plurality of first engaging holes formed at equal intervals in a circumferential direction in the first drive transmission member with predetermined margins in radial and circumferential directions, and the output-side coupling incline in an arbitrary direction with respect to the axis of rotation of the first drive transmission member, and the driving force from the drive transmission gear is transmitted to an outer circumferential rim of the first drive transmission member.