The present invention provides a method for continuously manufacturing a stretchable sheet (3) with a thread-shaped elastic body (7) fixed between a pair of belt-shaped sheets (50, 60) in a stretched state, the method including a supply process of introducing the fed thread-shaped elastic body (7) to elastic body winding means (14) in a stretched state, a conveyance process of continuously winding the thread-shaped elastic body (7) to a thread-conveying longitudinal structure (12, 13) using the elastic body winding means (14) and conveying the wound thread-shaped elastic body in a longitudinal direction of the structure (12, 14), and an integration process of fixing the thread-shaped elastic body (7) as sandwiching between the sheets (50, 60). In the supply process, the thread-shaped elastic body (7) is introduced to the elastic body winding means (14) while adjusting a speed of the thread-shaped elastic body (7) to be equal to or higher than a winding speed against the pair of conveying belts (12, 13) with speed adjusting means (15B) which is arranged at the upstream side of the elastic body winding means (14).
