The purpose of this research is to identify prospective mathematics teachers' conceptual structure about the concept of "Integral". In this research, phenomenology design, one of the qualitative research designs, was used. A total of 35 prospective mathematics teachers, studying at a state university, participated in the research. The Word Association Test was conducted to collect the data. The data were analyzed according to content analysis and categories were given according to frequency values. Conceptual networks that present prospective mathematics teachers' cognitive structure about integral concept were drawn by using a "cut-off point" technique according to the frequency table. As a result, 14 categories related to integral concept were obtained.