PROBLEM TO BE SOLVED: To provide a core adaptor which allows for production of a high quality wrinkle-free heat-resistant resin film substrate with high productivity.SOLUTION: In a pair of core adaptors 20 being attached to both sides of a cylindrical core 10 around which a long substrate F is wound, each core adaptor 20 consists of a first engaging part 21 abutting against the inclined plane 32 of a truncated conical taper cone 31 biased toward the core 10 over the entire circumference thereof, a second engaging part 24 engaging with one end face 11 of the core 10 via a flexible member 25, and an insertion part 23 being fitted in the core 10 from the end. An oblique winding coil spring 26 is wound around the outer peripheral surface 23a of the insertion part 23. This core adaptor 20 is used suitably in the take-up device of a long substrate F that is carried roll-to-roll in a vacuum chamber.
