Disclosed is a protective layer to protect a lithium metal negative electrode for a lithium secondary battery, in which the protective layer may inhibit formation of lithium dendrite and improve thermal/chemical stability, and conductivity of lithium ions. Further, disclosed are a production method of the protective layer, and a lithium secondary battery including the protectively layer. The protective layer contains a poly(arylene ether sulfone)-poly(ethylene glycol) graft copolymer represented by a following Chemical Formula 1: where, in the Chemical Formula 1, n is an integer of 60 to 80, and m is an integer of 40 to 45.