Measurement of teacher competence through TPACK is very important to do. However, the majority of the instruments used to measure TPACK for elementary school teachers are not yet in line with the needs of the 21st Century. This study aims to develop a TPACK instrument for elementary school teachers in a valid and reliable Mathematic lesson. This study uses the quantitative research. The study sample involved 1490 teacher in elementary school, grade IV, V, and VI teachers from state and private elementary schools with A level of accreditation, spread across fourteen sub-districts in the Kabupaten Bogor. Data analysis techniques use Winsteps 4.0.1. So that, overall, this instrument can be used to measure TPACK of elementary school teachers in the content of mathematics lessons. This instrument can be used to map teacher competencies based on TPACK values. Furthermore, if there are some weaknesses in the 7 aspects of the TPACK, policy makers can determine the follow-up that needs to be determined to further improve the competence of elementary school teachers. The dimensions that stand out in this research are lesson content, teaching approach, technology, pedagogy, content, and mathematics.