A research and developmental study about developing three tier test instrument was carried out to detect students’ conception on cell concept. Students’ pre-conception about cell concept, cell reproduction and gametogenesis are often not in line with scientific concepts. This preliminary study was conducted to analyze the profile of students’ pre-conception about cell reproduction in senior high schools. Modified Borg and Gall’s R&D research design used in this research. Instrument development resulted in three tier diagnostic test in the form of 30 multiple choice test items with its reason and certainty index. To validate the instrument, it was administered towards a number of senior high school students (XI and XII graders) in Bandung. Then the response of the students were quantitatively and qualitatively analyzed. Research findings show that the instrument as product is effective to determine students’ conception, including their misconception. The percentage of misconception found in cell concepts mostly in gametogenesis (17.35%), compared to those who comprehend (27.83%), and not comprehend (54.82%). The results of this preliminary study will then be used for further study in preparing STEM based learning program which will facilitate 12th grade students on conceptual change in cell reproduction, as well as to prevent its misconception.