A hemming device, comprising: an anvil for placing a work including a first plate member and a second plate member; a presser material handling portion for holding the work; a conveyance robot for gripping and conveying the presser material handling portion to bring the work to the anvil or bring out the work from the anvil, the conveyance robot including a robot-side Automatic Tool Changer, so-called ATC, device; and a roller hemming robot, wherein: the roller hemming robot hems a peripheral portion of the first plate member while pressing a hemming roller of a roller head to a portion to be processed of the work placed on the anvil until the peripheral portion has a final shape in which the peripheral portion and a peripheral portion of the second plate member overlap so that the first plate member and the second plate member are integrated; characterized in that the anvil includes an anvil main body portion, a first positioning device provided at a position corresponding to a position of an opening of the work, a first gripping device for sucking and gripping the first plate member, and a first device-side ATC device is configured to be attached to and detached from the robot-side ATC device; and the presser material handling portion includes a frame portion having a shape corresponding to a shape of the work, a second positioning device arranged at a position corresponding to a position of the first positioning device and engaged with the first positioning device, a second gripping device for sucking and gripping the first plate member through an opening of the second plate member, a presser for pressing the second plate member, the presser being provided at a position at which the presser does not interfere with the final shape, and a second device-side ATC device is configured to be attached to and detached from the robot-side ATC device. an anvil for placing a work including a first plate member and a second plate member; a presser material handling portion for holding the work; a conveyance robot for gripping and conveying the presser material handling portion to bring the work to the anvil or bring out the work from the anvil, the conveyance robot including a robot-side Automatic Tool Changer, so-called ATC, device; and a roller hemming robot, wherein: the roller hemming robot hems a peripheral portion of the first plate member while pressing a hemming roller of a roller head to a portion to be processed of the work placed on the anvil until the peripheral portion has a final shape in which the peripheral portion and a peripheral portion of the second plate member overlap so that the first plate member and the second plate member are integrated; characterized in that the anvil includes an anvil main body portion, a first positioning device provided at a position corresponding to a position of an opening of the work, a first gripping device for sucking and gripping the first plate member, and a first device-side ATC device is configured to be attached to and detached from the robot-side ATC device; and the presser material handling portion includes a frame portion having a shape corresponding to a shape of the work, a second positioning device arranged at a position corresponding to a position of the first positioning device and engaged with the first positioning device, a second gripping device for sucking and gripping the first plate member through an opening of the second plate member, a presser for pressing the second plate member, the presser being provided at a position at which the presser does not interfere with the final shape, and a second device-side ATC device is configured to be attached to and detached from the robot-side ATC device. the roller hemming robot hems a peripheral portion of the first plate member while pressing a hemming roller of a roller head to a portion to be processed of the work placed on the anvil until the peripheral portion has a final shape in which the peripheral portion and a peripheral portion of the second plate member overlap so that the first plate member and the second plate member are integrated; characterized in that the anvil includes an anvil main body portion, a first positioning device provided at a position corresponding to a position of an opening of the work, a first gripping device for sucking and gripping the first plate member, and a first device-side ATC device is configured to be attached to and detached from the robot-side ATC device; and the presser material handling portion includes a frame portion having a shape corresponding to a shape of the work, a second positioning device arranged at a position corresponding to a position of the first positioning device and engaged with the first positioning device, a second gripping device for sucking and gripping the first plate member through an opening of the second plate member, a presser for pressing the second plate member, the presser being provided at a position at which the presser does not interfere with the final shape, and a second device-side ATC device is configured to be attached to and detached from the robot-side ATC device.