Provided are a separator, a method of manufacturing the separator, and an electrochemical device including the separator. According to an exemplary embodiment of the present disclosure, a separator including a porous substrate and an inorganic particle layer provided on at least one surface of the porous substrate, the inorganic particle layer including inorganic particles, a hydrolytic condensate binder of a polar silane compound, and an aqueous polymer binder, wherein an amount of change in peel strength, △P, represented by the following Equation (1) is 1.1 or more may be provided: Δ P = P 1 / P 2 wherein
P 1 is peel strength of the separator,
P 2 is peel strength of a separator including a porous substrate and an inorganic particle layer which is provided on at least one surface of the porous substrate and includes boehmite particles and a hydrolytic condensate of (3-aminopropyl)triethoxysilane, and
the peel strength is measured by adhering a double-sided tape having a width of 15 mm and a length of 60 mm from one end in a length direction on a copper plate having a thickness of 200 µm, a width of 15 mm, and a length of 100 mm, adhering the separator thereon by stacking and pressing so that the tape faces the inorganic particle layer of the separator, and using UTM equipment to perform a 180° peel test under conditions of a speed of 300 mm/min and a displacement of 100 mm.