This study aims to analyze and to describe, in terms of information processing theory, the thinking processes of junior high school students as they solved problems involving direct and inverse proportions. This study design is qualitative and exploratory-descriptive in nature. 26 students in the seventh grade of SMP Negeri 1 Kota Ternate were assigned direct and inverse proportion assignments. Eventually, based on the students' thinking potential and verbal and written communication skills, 3 students who could describe the thinking process based on information processing theory components were selected. The instruments for data collection consisted of questions on direct and inverse proportions, supported by interview procedures. Based on the analysis and discussion of research results, three categories of student thinking processes can be identified: (1) multiple thinking categories in solving direct proportion problems, which occur in the perception component when S1 students write or express problem solving plans using multiple strategies to process accepted information; (2) the multiplication thinking category in solving inverse proportion problems, which occurs in the perception component; and (3) the generalization thinking category in solving inverse proportion problems, which occurs in the perception component.