The present disclosure relates to a duct cutting and forming apparatus for elbow duct manufacturing machine, the apparatus including a rotation housing that is provided with a seating groove in a first direction; an eccentric housing that is provided with a cutting roller and a forming roller at both ends, and that is slidably seated inside the seating groove; a rotation drive for applying rotation driving force to the rotation housing; and an eccentric drive for applying driving force for reciprocating the eccentric housing, wherein the eccentric drive reciprocates the eccentric housing as it rotates in both directions within a range not exceeding 180 degrees.