(EN) Disclosed is a separator for an electrochemical element, which is characterized by comprising a heat-resistant porous layer that is mainly composed of heat-resistant fine particles on at least one surface of a resin porous film that is mainly composed of a thermoplastic resin. The separator for an electrochemical element is also characterized in that: the resin porous film has a surface tension (wetting index) A of 35 mN/m or less; the heat-resistant porous layer is formed of a heat-resistant porous layer-forming composition that contains an aqueous medium and has a surface tension B of less than 29 mN/m; and the relation between the surface tension (wetting index) A and the surface tension B satisfies A > B.