Problem solving is not simply a process that ends when an answer is found; it is a scientific process that evolves from understanding the problem to evaluating the solution. This process is affected by several factors. Among these, one of the most substantial is belief. The purpose of this study was to evaluate the beliefs of high school students according to their explanations in the problem solving process. A case study was carried out with five students. Each of the students' problem solving processes was examined by means of clinical interviews and three problems were presented to the students. The results illustrate that the students who thought problem solving should be a short process and that they could address it by memorization of rules also believed that problem solving is difficult. This study concludes that not only beliefs affect the problem solving process, but also personal factors such as life experiences.