An electrode active material forming composition, a separator forming composition and a manufacturing method of a lithium secondary battery using the compositions are provided. The method for manufacturing a lithium secondary battery including the steps of (a) coating electrode active material compositions each comprising a electrode active material, a binder and a solvent on an electrode current collector to form a cathode and an anode, (b) forming a separator on both surfaces of the anode using a composition for forming a separator comprising a polymer resin, a plasticizer, a filler and a solvent; (c) disposing and fixedly adhering the cathode on the separator to form a battery structure, (d) drying the battery structure under a vacuum condition, and (e) impregnating an electrolytic solution into the resultant structure, wherein the plasticizer of the composition for forming the separator is at least one material selected from the group consisting of an ethylene glycol derivative, a cyclic carbonate, a non-cyclic carbonate and propylene glycol carbonate. Therefore, since a plasticizer can be removed under a vacuum condition, the time required for manufacturing a battery can be reduced and the manufacturing process becomes simplified, thereby improving the productivity. Also, since an organic solvent extraction process using an organic solvent is not necessary, unlike in the conventional art, the cost required for a recovery facility of an organic solvent can be reduced. Further, uniform pores are formed in electrodes and a separator, the porosity characteristics are excellent, and adhesion between the separator and the electrodes is excellent, thereby exhibiting excellent high-rate, lifetime, and low-temperature characteristics.