A transmission mechanism for transmitting rotation of a driving source in a main body to an object mounted on the main body for receiving the rotation, the transmission mechanism comprising a plurality of couplings provided at different positions along an axial direction of a rotating axis; wherein each of the couplings comprises, a male coupling member having a plurality of protrusions provided at an identical internal on an outer circumferential surface of the rotating axis; and a female coupling member having a plurality of protrusions for engaging with the male coupling's protrusions.