There is provided an anastomosis system for performing an anastomosis in a body. The system includes an anastomosis button, which has two foldable flange portions and a tubular main body portion extending between the flange portions, for coupling two lumen portions in the body to each other, and a housing which can receive the anastomosis button as the flange portions are folded. The system further includes a guide, which has a distal end to be inserted through a patient's mouth to a target portion in the body and a proximal end arranged outside the body, for guiding the housing to the target portion. A release line having a distal end to be inserted to the target portion along the guide and a proximal end held outside the body is operated, whereby the anastomosis button can be ejected from the housing and be held at the target portion.