PURPOSE: To always take out a stable signal of completion of winding and endure high-speed rotation by providing a light source and a light receiving element, forming a winding detection means, in opposition to each other on the outer peripheral side and the inner peripheral side of the winding core, on the core part of a sheet winding device.

CONSTITUTION: A winding detector of a sheet winding device is composed of a lamp 23 and a photosensor 24. The lamp 23 and the photosensor 24 are respectively arranged inside the hollowness of a winding core 18 and in the vicinity of the tip of a guide plate 14 in such a manner as they are in opposition to each other with a film winding wall 18b of the winding core 18 interposed between them. Although a light from the lamp 23 is received by the sensor 24 while the film is not wound on said core 18, when the tip of the film is wound on the core 18, the light from the lamp 23 is intercepted and a signal of completion of winding is generated from the sensor 24. Power supply to a motor 7 is stopped due to this signal and solenoid 9 becomes inoperative, and a capstan roller 6 moves to a position separated from a microfilm. The film is later fed to the reel 12 consecutively.