A drive transmission mechanism including a drive shaft, a rotational driving member having at least two first protrusions and provided to the drive shaft, a driven member having at least two second protrusions and provided to a rotary shaft of a rotary member, deformable connecting parts provided to at least one of portions between the first protrusions and the rotational driving member and portions between the second protrusions and the driven member, and an elastic member covering the deformable connecting parts. The deformable connecting parts displace one of the first and second protrusions relative to one of the rotational driving member and the driven member in a direction tangential to a direction of rotation of the rotational driving member and the driven member upon contact of the first protrusions with the second protrusions.