A drive transmission device includes a rotation shaft, a drive transmitter attached to the rotation shaft to slide in an axial direction and including an engaging portion extending in the axial direction, and a coil spring to bias the drive transmitter to one side in the axial direction, and a shaft-side drive transmitter disposed on the rotation shaft. The coil spring includes a sparse portion and a dense portion. The shaft-side drive transmitter engages the engaging portion to prevent the drive transmitter from disengaging from the rotation shaft. The coil spring and the engaging portion satisfy C>A−B where A represents a length of the coil spring in a state in which the shaft-side drive transmitter retains the drive transmitter, B represents a compressed height of the coil spring, and C represents a length of the coil spring in the axial direction.