Disclosed are a separator for a lithium secondary battery and a lithium secondary battery comprising same. The separator for a lithium secondary battery comprises: a porous substrate; and a coating layer disposed on at least one side of the porous substrate, wherein the coating layer contains heat-resistant organic particles, an organic heat-resistant binder, and an organic adhesive binder, wherein the heat-resistant organic particles have a thermal decomposition temperature of 150° C. or higher and a particle diameter of 100 nm to 300 nm, the organic heat-resistant binder is a first organic material having a glass transition temperature of 130° C. to 200° C., the organic adhesive binder is a second organic material having a glass transition temperature of −40° C. or lower, and the mixing weight ratio of the organic heat-resistant binder and the organic adhesive binder is 7:3 to 9:1.