Women are underrepresented in STEM. Researchers note that gender stereotypes are the main explanation for gender disparities in STEM. Methods for measuring stereotypes do not take into account the contexts of education and careers in STEM. This study is an attempt to develop a tool for measuring stereotypes, using mix methods approach. At the first stage (qualitative research), the factor structure of the instrument was determined (method interview, sample of 18 women); at the second stage (quantitative research), a questionnaire on stereotypes in STEM was developed and tested (sample of 145 women). The developed questionnaire demonstrates satisfactory psychometric characteristics, correct functioning of statements and confirms the expected two-factor structure. The questionnaire consists of 10 statements and includes two factors: (1) studying STEM and career in STEM are more suitable for men than women; (2) work in STEM is not compatible with the female role model of taking care of the family. The selected factor model correlates with theoretical ideas about stereotypes: stereotypes about girls' abilities in technical disciplines and stereotypes about female role model. The developed questionnaire "STEM stereotypes" will make it possible to fix them, evaluate their relationship with other psychological constructs (for example, motivation) and academic achievements, correct the educational and career trajectory, thereby possibly contributing to the consolidation women in STEM.