Disclosed is a separator for an electrochemical device which comprises: a porous substrate having a plurality of pores; and a porous coating layer positioned on at least one surface of the porous substrate, and including a plurality of inorganic particles and a binder polymer positioned on the whole or a part of the surface of the inorganic particles to connect the inorganic particles with one another and fix them, wherein the binder polymer comprises a first binder polymer and a second binder polymer, the first binder polymer has an electrolyte uptake of 80-165%, and the second binder polymer has an electrolyte uptake of 20-40%. An electrochemical device including the separator is also disclosed.