A developing device includes: a housing made of resin; a developer carrier, which is rotatably supported by the housing, and which is configured to carry developer on a circumferential surface thereof; a receiving-side coupling member, which is provided rotatably to one of end portions of the developer carrier and is configured to couple with a driving-side coupling member in the rotational axial direction to transmit driving force to the developer carrier; a blade, which is provided along the rotational axial direction, and which configured to contact the circumferential surface of the developer carrier to regulate a layer thickness of the developer on the circumferential surface; and a support member, which is bent into an L-shape as viewed from the rotational axial direction, and which supports the blade, wherein the receiving-side coupling member is overlapped with a bending portion of the support member, as viewed from the rotational axial direction.