To provide a compound slider for a fastener which is capable of attaching/detaching two flexible members with fasteners without exposing the inner space to the outer space.

The compound slider for a fastener, attaching/detaching the first flexible member and the second flexible member, includes: the first slider part 10; the second slider part; the third slider part 20; and the fourth slider part 21. The branch parts of these slider parts are facing with each other. The third slider part 20 is twisted at almost right angle against the first slider part 10, and the fourth slider part 21 is twisted at almost right angle against the second slider part.