An improved annular blowout preventer having a body with a central bore, an annular packer chamber facing the bore, an improved annular packer in said chamber and means for axially loading said annular packer to actuate it to closed position, said improved annular packer including a resilient annulus including an upper set of insert plates embedded in said annulus, a reaction ring embedded in the outer periphery of said annulus and means for moving said reaction ring toward said upper set of insert plates responsive to actuation of said packer loading means to ensure inward movement of said insert plates to their desired supporting position for said annulus when closed. The improved packer may have both upper and lower insert plates and upper and lower rings and a sleeve within the rings to ensure proper movement of both sets of insert plates.