The research aims to describe students' mathematical justification skills in
SMP Negeri 1 Purbalingga reviewed from gender. The research method is
qualitative descriptive. The research subjects are grade VII D students of
SMP Negeri 1 Purbalingga taken through purposive sampling. The data
collection techniques are tests, interviews, and documentation. The data were
analyzed using Miles and Huberman's model of data reduction, data display,
taking conclusion, and verification. Data validity was obtained through the
triangulation technique. The research result shows that male students are able
to master three indicators of mathematical justification skill, namely: 1)
arranging evidence, reasoning or giving evidence about the truth of the
solution, and taking conclusion, 2) classifying objects properly based on
certain characteristics which are in line with the concept, and 3) displaying
the concept in various mathematics representation. Moreover, it is also
revealed that female students are able to master three indicators of
mathematical justification skills, namely: 1) proposing a presumption, 2)
arranging evidence, reasoning or giving evidence about the truth of the
solution, taking conclusion, and 3) displaying concept in various mathematics
representation.