Researchers have been keen to develop instruments for the assessment of teachers' self-perceived technological pedagogical content knowledge (TPACK); however, few studies have been conducted to validate such assessment tools through students' perspectives in the context of English as a foreign language (EFL). The purpose of this study was thus to develop a TPACK instrument that can be utilized to investigate EFL students' perceptions of their teachers' TPACK. Thirty-five survey questions were initially created through a literature review and then reviewed by experts, teachers, and students. Exploratory factor analysis was undertaken to ensure the validity of this scale and Cronbach's alpha was adopted to evaluate the internal consistency of the survey. The results revealed that the TPACK instrument was a valid and reliable tool for measuring EFL students' perceptions of their teachers' TPACK. Finally, suggestions are offered for future studies regarding the use of the TPACK instrument in the assessment of teachers' TPACK.