A seating device includes a seat body, a headrest movably connected to the seat body; an adjustment mechanism connected between the seat body and the headrest to adjust a position of the headrest; and an operating unit movably mounted to the headrest and having a driving member configured to actuate the adjustment mechanism. The driving member is movable in a top-bottom direction between a non-operative position and an operative position. The adjustment mechanism includes a driven member movably mounted to the headrest. The driving member has an active transmitting part. The driven member has a passive transmitting part configured to engage the active transmitting part in the operative position and disengage from the active transmitting part in the non-operative position. The driving member is configured to transmit an actuation movement to the driven member in response to the passive transmitting part engaging the active transmitting part.