This Mathematics is known as a lesson that requires students to explain the process before answering, through the essay questions will be able to find out the errors made in answering the questions. This research aims to analyze students' error in doing the mathematics problems in terms of students' learning styles. Error analysis was carried out based on the Kastolan method. The research method used is descriptive qualitative. Data was collected using instruments in the form of a essay test on squared root material, a learning style questionnaire, and an interview sheet guide. The subjects in this research were junior high school students in class IXC. The results of research showed that subjects who have a visual learning style made the most concept errors. Furthermore, technical errors were made by all subjects, visual, kinesthetic and auditory subjects. Procedural errors were only made once by subjects in the auditory learning style. The percentage of concept and technical errors is the equal of 67%,. Based on the results obtained, it shows that each learning style has its advantages and disadvantages so they made the different errors when doing the mathematics problems.

Keywords: Error analysis; mathematics; learning styles; Kastolan’s theory