Abstract: A door closer includes: a cylinder secured on a door frame and having a cylinder head formed on a proximal end of the cylinder; a main value and a check valve respectively formed on the cylinder head to control the air in-and-out volume through the valves for lightly opening the door; a piston secured to a rod member slidably reciprocating within the cylinder with the rod member secured to a door; a restoring spring secured between the cylinder head and the rod member for normally resiliently restoring the rod member and the piston towards the cylinder head in order to close the door to the door frame normally as restored by the restoring spring; and at least a buffer member secured between the cylinder head and the piston so as to dampen the inertia force of the closing door to eliminate the noise or damage thus possibly caused.