A door closer having a return spring for accumulating a recovering force in a door closing direction at the time of opening a door for performing a braking force by a damper at the time of closing the door which comprises a closer body internally containing a mechanism for performing an operation as the damper in a body case, an adjusting arm coupled perpendicularly to a driving shaft for the damper of the closer body to be projected laterally rotatably, a coupling bracket for pivotally securing an upper frame mounting plate directly or indirectly to the end of the adjusting arm via step screws to be horizontally rotatable, and a door mounting arm projected laterally from the closer body for pivotally securing a door mounting bracket to the end of the arm via a step screw to be horizontally rotatable. Thus, the door closer can obviate a concept of mounting the closer body at the door to eliminate necessity of mounting a large closer body at the door by disposing a closer body as a damper at the pivotally securing position of the arm and the adjusting arm, thereby deleting impossibility of mounting the door closer even at a glass engaging door.