However, when the World War II broke out, sericulture declined due to various reasons, including changes in crop (from mulberry to sweet potato) to prevent food shortages, price reduction of yarn itself, the appearance of chemical fibers such as nylon fibers, lack of successors in silk-raising farmers, aging of silk-raising farmers, etc., all factors leading to a decline and the eventual closeout by silk-raising farmers and yarn-making companies.
しかし第二次世界大戦になると食糧不足解消のため、桑畑をサツマイモ畑に転作したことや、糸そのものの価格の低下、ナイロンなどの化学繊維の出現や養蚕農家の後継者不足と高齢化などのさまざまな理由によって養蚕業の衰退を招き、これらをきっかけにほとんどの養蚕農家や製糸業者は廃業に追い込まれた。