To fix a cut end part of a rubber thread in a desired bonding pair in a stretchable sheet which fits the rubber thread to a sheet part with a pair of bonding parts located on both sides of the rubber thread.SOLUTION: A manufacturing method of a stretchable sheet (10) arranges a stretched rubber thread (14) in a horizontal direction between a first sheet part (11) and a second sheet part (12), forms a plurality of bonding parts (j) crimping and bonding the first sheet part (11) and the second sheet part (12), cuts the rubber thread (14) at a cut position in the horizontal direction after the stretch state of the rubber thread (14) is relieved, and regulates a position of the rubber thread (14) in the lateral direction by putting after cutting the rubber thread (14) shrunk between a pair of bonding parts (jP) on both sides of the rubber thread (14). In a step relieving the rubber thread (14), the stretching state of at least one part of the rubber thread (14) on one side of the cut position and at least one part of the rubber thread (14) on the other side of the cut position in the lateral direction are relieved.SELECTED DRAWING: Figure 7【課題】糸ゴムの両側に位置する接合部対で糸ゴムをシート部に取り付ける伸縮性シートにおいて、所望の接合部対で糸ゴムのカット端部を固定すること。【解決手段】伸縮性シート（１０）の製造方法であって、第１シート部（１１）と第２シート部（１２）の間に横方向に伸長状態の糸ゴム（１４）を配置し、第１シート部（１１）と第２シート部（１２）を圧着接合する複数の接合部（ｊ）を形成し、糸ゴム（１４）の伸長状態を緩和させた後に、横方向の切断位置にて糸ゴム（１４）を切断し、切断後では収縮した糸ゴム（１４）が糸ゴム（１４）の両側の接合部対（ｊＰ）に挟まれて、糸ゴム（１４）の横方向の位置が規制され、糸ゴム（１４）を緩和させる工程では、横方向において切断位置よりも一方側の少なくとも一部分及び切断位置よりも他方側の少なくとも一部分の糸ゴム（１４）の伸長状態を緩和させること。【選択図】図７
