A back shaver includes a cutter head assembly and a handle. The handle is connected to the cutter head assembly. The cutter head assembly includes a cutter head frame, cutter heads, and a connecting member. The cutter heads are embedded in a front surface of the cutter head frame. A back surface of the cutter head frame is connected to the connecting member through rotating shafts. An additional weight mechanism is disposed on the back surface of the cutter head frame, and the additional weight mechanism is further disposed close to an upper edge of the back surface of the cutter head frame. The present disclosure has advantages of simple design and structure, good hand feeling, effortless operation, which achieves good shaving effect.