Conclusion of Treaties Act Article 4

The Ministry of Foreign Affairs (hereinafter referred to as “MOFA”) shall be in charge of the signature of treaties and agreements, unless a treaty or an agreement is specialized or technical in content, and has been approved by MOFA or the Executive Yuan.The competent authorities' appointment of delegates and issuance of full powers for the negotiation of treaties and agreements shall be in accordance with international conventions and practices.
中文原文 條約締結法第4條
條約及協定之簽訂,由外交部主辦。
但條約及協定內容具有專門性、技術性,且經外交部或行政院同意者,不在此限。
主辦機關就條約及協定談判及簽署代表之指派與全權證書之頒發,應依國際公約及慣例辦理。

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