Separator for electric storage device and electric storage device

[Problem] To provide a separator for electric storage devices that suppresses dendrite short circuits and has excellent thermal stability. [Solution] Provided is a separator for electric storage devices including: (A) a microporous layer mainly composed of (X) isotactic polypropylene; and (B) a microporous layer containing (Y) isotactic polypropylene identical or different from the isotactic polypropylene (X), and (Z) thermoplastic resin different from the isotactic polypropylene (Y). The microporous layer (B) has a lower isotactic polypropylene content than the microporous layer (A), and the thermoplastic resin (Z) has a tensile modulus of from 3 MPa to 500 MPa.