Immigration Act Article 28

An alien, who is aged of fourteen (14) or over, and has entered the State for a visit, residence or permanent residence, shall always carry his/her passport, Alien Resident Certificate, or Alien Permanent Resident Certificate.The National Immigration Agency or public servants under other laws and orders can reuqest aliens to produce the documents stated in the preceding Paragraph while performing official duties. With respect to the requirements and procedures of perform the above-mentioned duties, the provisions of Chapter 2 of the Police Duties Enforcement Act shall apply mutatis mutandis.
中文原文 入出國及移民法第28條
十四歲以上之外國人,入國停留、居留或永久居留,應隨身攜帶護照、外僑居留證或外僑永久居留證。
移民署或其他依法令賦予權責之公務員,得於執行公務時,要求出示前項證件。
其相關要件與程序,準用警察職權行使法第二章之規定。

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