A separator, comprising a porous composite having a porous substrate and a first porous coating layer formed on at least one surface of the porous substrate and comprising a mixture of inorganic particles and a first binder polymer; and a second porous coating layer formed on a first surface of the porous composite and comprising a mixture of cathode active material particles, a second binder polymer and a first conductive material, a third porous coating layer formed on a second surface of the porous composite and comprising a mixture of anode active material particles, a third binder polymer and a second conductive material, or both of the second porous coating layer and the third porous coating layer, wherein the separator is obtainable by a method for manufacturing a separator comprising the steps: preparing a planar porous substrate having multiple pores; coating an inorganic particle slurry obtained by dissolving a first binder polymer in a first solvent and dispersing inorganic particles therein on at least one surface of the porous substrate; coating a cathode active material particle slurry obtained by dissolving a second binder polymer in a second solvent and dispersing cathode active material particles and a first conductive material therein, an anode active material particle slurry obtained by dissolving a third binder polymer in a third solvent and dispersing anode active material particles and a second conductive material therein, or both of the cathode active material particle slurry and the anode active material particle slurry on the coated inorganic particle slurry; and simultaneously carrying out a dry-treatment for the second solvent or the third solvent together with the first solvent to first dry the second solvent or the third solvent and form the second porous coating layer or the third porous coating layer, thereby preventing the penetration of the first conductive material or the second conductive material into the pores of the porous substrate by the inorganic particle slurry, and then to dry the first solvent and form the first porous coating layer. preparing a planar porous substrate having multiple pores; coating an inorganic particle slurry obtained by dissolving a first binder polymer in a first solvent and dispersing inorganic particles therein on at least one surface of the porous substrate; coating a cathode active material particle slurry obtained by dissolving a second binder polymer in a second solvent and dispersing cathode active material particles and a first conductive material therein, an anode active material particle slurry obtained by dissolving a third binder polymer in a third solvent and dispersing anode active material particles and a second conductive material therein, or both of the cathode active material particle slurry and the anode active material particle slurry on the coated inorganic particle slurry; and simultaneously carrying out a dry-treatment for the second solvent or the third solvent together with the first solvent to first dry the second solvent or the third solvent and form the second porous coating layer or the third porous coating layer, thereby preventing the penetration of the first conductive material or the second conductive material into the pores of the porous substrate by the inorganic particle slurry, and then to dry the first solvent and form the first porous coating layer.