Disclosed is an apparatus for manufacturing a long-neck flange comprising: a pipe support bar for supporting the inside of a pipe, the pipe support bar being rotatable; a rotatable pressurizing device connected to the pipe support bar for simultaneously rotating, pressurizing, and conveying the pipe with one end fixed thereto; a face roller for contacting a cross section of the pipe support bar to form a flange surface; a curvature roller positioned at the outside of the pipe for giving a curvature to the flange part; and a circumferential roller positioned at the outside of the pipe in the circumferential direction so as to form the width of the flange part.