A drive transmission device includes a driving-side coupling, a driven-side coupling, and an intermediary transmission member provided therebetween. The driving-side coupling and the intermediary transmission member engage with each other so as to be movable in a first direction. The driven-side coupling and the intermediary transmission member engage with each other so as to be movable in a second direction crossing the first direction. The intermediary transmission member is held by a holding-side coupling which is one of the driving and the driven-side couplings or by a shaft member engaging with the holding-side coupling. Engagement of the intermediary transmission member with a non-holding-side coupling which is the other coupling permits a deviation angle about an axis extending in the first direction and a deviation angle about an axis extending in the second direction.