The present invention refers to a separator for an electrochemical device and an electrochemical device having the same. More specifically, the separator of the present invention comprises a porous substrate; a first porous coating layer formed on 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 the other surface of the porous substrate and comprising a product obtained by drying a mixture of a solvent, a non-solvent and a second binder polymer.Such separator of the present invention can have good thermal safety due to a porous organic-inorganic coating layer formed on one surface thereof, and superior adhesiveness due to a porous coating layer made of a binder thin film formed by applying and drying a mixture of a binder polymer and a non-solvent on the other surface thereof. Also, the separator can have a decreased thickness to reduce the resistance of electrochemical device and improve the capacity thereof.