This was a descriptive qualitative research which aimed to describe the
student's understanding ability of mathematical concept on the eighth grade viewed from
the difference of gender on the material of block and cube. The subjects of this research
were the students in Class VIII B of SMP Negeri 1 Patikraja who were taken using
purposive sampling and consisted of 3 students as the respondents for each gender. The
data were collected using test, interview, and documentation. The results showed that
male student was able to master two indicators of understanding skill of mathematical
concept which were presenting a concept in many forms of mathematical representation
and developing the necessary and sufficient conditions from a concept. Meanwhile, the
female student was able to master three indicators such as presenting a concept in many
forms of mathematical representation, logically implementing a concept on problem
solving, and developing the necessary and sufficient conditions from a concept.