A positive electrode for a secondary battery, the positive electrode comprising a positive electrode active material layer formed on a positive electrode collector, wherein the positive electrode active material layer has a double-layer structure which includes a first positive electrode active material layer formed on the positive electrode collector and a second positive electrode active material layer formed on the first positive electrode active material layer, the first positive electrode active material layer comprises a first positive electrode active material, a conductive agent, and a volume expansion resin in which volume expansion occurs at a high temperature during overcharge, and the second positive electrode active material layer comprises a second positive electrode active material; wherein: the first positive electrode active material is an olivine-structured positive electrode active material represented by Formula 1: [Formula 1] Li 1+a1 Fe 1-x1 M x1 (PO 4-y1)X y1 wherein, in Formula 1, M is at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), gallium (Ga), copper (Cu), vanadium, niobium (Nb), zirconium (Zr), cerium (Ce), indium (In), zinc (Zn), and yttrium, X is at least one element selected from the group consisting of fluorine, sulfur, and nitrogen, -0.5≤a1≤0.5, 0≤x1≤0.5, and 0≤y1≤0.3; the second positive electrode active material is represented by Formula 2: [Formula 2] Li 1+x (Ni a Co b M' c) 1-x O 2 wherein, in Formula 2, M' is at least one element selected from the group consisting of Mn, Al, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn, and Y, 0<a<1, 0<b<1, 0<c<1, -0.1≤x≤0.2, and a+b+c=1; and the volume expansion resin comprises at least one selected from the group consisting of polyethylene, polypropylene, and poly(ethylene-vinyl) acetate). wherein the positive electrode active material layer has a double-layer structure which includes a first positive electrode active material layer formed on the positive electrode collector and a second positive electrode active material layer formed on the first positive electrode active material layer, the first positive electrode active material layer comprises a first positive electrode active material, a conductive agent, and a volume expansion resin in which volume expansion occurs at a high temperature during overcharge, and the second positive electrode active material layer comprises a second positive electrode active material; wherein: the first positive electrode active material is an olivine-structured positive electrode active material represented by Formula 1: [Formula 1] Li 1+a1 Fe 1-x1 M x1 (PO 4-y1)X y1 wherein, in Formula 1, M is at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), gallium (Ga), copper (Cu), vanadium, niobium (Nb), zirconium (Zr), cerium (Ce), indium (In), zinc (Zn), and yttrium, X is at least one element selected from the group consisting of fluorine, sulfur, and nitrogen, -0.5≤a1≤0.5, 0≤x1≤0.5, and 0≤y1≤0.3; the second positive electrode active material is represented by Formula 2: [Formula 2] Li 1+x (Ni a Co b M' c) 1-x O 2 wherein, in Formula 2, M' is at least one element selected from the group consisting of Mn, Al, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn, and Y, 0<a<1, 0<b<1, 0<c<1, -0.1≤x≤0.2, and a+b+c=1; and the volume expansion resin comprises at least one selected from the group consisting of polyethylene, polypropylene, and poly(ethylene-vinyl) acetate). the first positive electrode active material is an olivine-structured positive electrode active material represented by Formula 1: [Formula 1] Li 1+a1 Fe 1-x1 M x1 (PO 4-y1)X y1 wherein, in Formula 1, M is at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), gallium (Ga), copper (Cu), vanadium, niobium (Nb), zirconium (Zr), cerium (Ce), indium (In), zinc (Zn), and yttrium, X is at least one element selected from the group consisting of fluorine, sulfur, and nitrogen, -0.5≤a1≤0.5, 0≤x1≤0.5, and 0≤y1≤0.3; the second positive electrode active material is represented by Formula 2: [Formula 2] Li 1+x (Ni a Co b M' c) 1-x O 2 wherein, in Formula 2, M' is at least one element selected from the group consisting of Mn, Al, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn, and Y, 0<a<1, 0<b<1, 0<c<1, -0.1≤x≤0.2, and a+b+c=1; and the volume expansion resin comprises at least one selected from the group consisting of polyethylene, polypropylene, and poly(ethylene-vinyl) acetate).