The present invention provides a caulked assembly to be manufactured at low cost, and maintain sufficient caulking strength, and the manufacturing method and apparatus thereof. The manufacturing method comprises steps of forming a mounting hole for inserting and assembling a columnar body in a metal plate body, and forming a thick part along an inner circumferential edge of a mounting hole; forming a circumferential groove with a predetermined depth at an assembled position of a outer circumferential surface of the columnar body inserted into the mounting hole; inserting the columnar body into the mounting hole to set to the assembled position where the thick part is opposed to the circumferential groove; and caulking for compressively pressing the thick part from an axial direction of the columnar body to plastically deform the thick part in a center direction of the mounting hole to bite the thick part into the circumferential groove.