Separator and its manufacturing method for an electrochemical device

PROBLEM TO BE SOLVED: To provide a separator for electrochemical elements having improved thermal resistance, electrolyte retention, and electrode durability, and to provide a method for manufacturing the separator. SOLUTION: The separator for electrochemical elements consists of a wet nonwoven fabric having total aromatic polyester fiber of >=10% on the surface thereof and having total aromatic polyamide fiber of >=10% on the opposite surface thereof. In the method for manufacturing the separator for electrochemical elements, the layer containing total aromatic polyester fiber of >=10% and the layer containing total aromatic polyamide fiber of >=10% are made and joined together. Heat treatment is preferably carried out at 150 deg.C-250 deg.C.