Unless granted exemption, yes, you will be required to take the Qualifying English Test (QET), which determines whether you would have to take English Proficiency as a subject of study. Students who fail the QET must take the said subject, English Proficiency course (HW0001).

For example, those who are exempted include those who scored a minimum of 6 for the Writing sub-test in IELTS or a minimum of 570 and above (PBT) or 90 and above (IBT) in TOEFL. You may check http://www.ntu.edu.sg/Students/Undergraduate/AcademicServices/Matriculation/Pages/CriteriaforQET.aspx for more information on this matter. See you soon!