The study aimed to describe the students' comprehensive ability on mathematical concept viewed from parents' educational background on the material of functions in class VIII A SMP Negeri 5 Purwokerto. It was a qualitative descriptive study. The data sources were selected by using purposive sampling technique. The students were classified into five groups namely the combination of parents' educational background. The data were collected by using questionnaires, tests, interviews, and documentations. The results revealed that (1) the subjects with higher education-higher education could clarify the objects based on given characteristics as its concept, give examples and not the example of the concept, use and utilize as well as select the procedures, develop necessary conditions or sufficient conditions for the concept, and display the concept in the form of mathematical representation. (2) the subjects with higher education – secondary education could clarify the objects based on given characteristics as its concept and display the concept in the form of mathematical representation. (3) the subjects with secondary education – secondary education could clarify the objects based on given characteristics as its concept, give examples and not the example of the concept, use and utilize as well as select the procedures, develop necessary conditions or sufficient conditions for the concept, implement the concept or algorithm in solving the problem, as well as display the concept in the form of mathematical representation. (4) the subjects with secondary education – primary education could clarify the objects based on given characteristics as its concept, develop necessary conditions or sufficient conditions for the concept, as well as display the concept in the form of mathematical representation. (5) the subjects with primary education – primary education could develop necessary conditions or sufficient conditions for the concept.