The invention provides an automatic tappet rod body machining device, and belongs to the field of tappet rod body machining equipment. The automatic tappet rod body machining device comprises an automatic workpiece supply device, a clamping device and a machining device body. The clamping device comprises a rotatable clamp body and a clamping mechanism, wherein the clamping mechanism is arranged on the clamp body. The automatic workpiece supply device is used for pushing a tappet rod body to the clamp body. The clamping mechanism is used for tightly clamping the tail of the tappet rod body. A tool surface is arranged on the clamp body, and is the end surface of the portion, close to the head portion of the clamped tappet rod body, of the clamp body, and when the clamp body rotates, the tool surface faces the machining device body or the side of the tool surface faces the machining device body. By the adoption of the automatic tappet rod body machining device, the purpose that both the end surface of the head portion of the tappet rod body and the circumferential surface of the head portion of the tappet rod body can be machined can be achieved in the one-time clamping process, repeated clamping does not need to be conducted, the working time is shortened, the production efficiency is improved, the degree of automation is relatively high, and the production cost is reduced.