Negotiable Instruments Act Article 15

The legal force and effect of a genuine signature on a negotiable instrument shall not be affected even if the instrument itself or one of the signatures thereon is forged.
中文原文 票據法第15條
票據之偽造或票上簽名之偽造,不影響於真正簽名之效力。

English translation for reference only; the Chinese text prevails. Not legal advice.