The aim of this study was to examine prospective science teachers' pedagogical content knowledge in terms of their approach to error. For this purpose, a data collection tool consisting of 5 questions for conceptual understanding of electrical circuits and steps containing correct and incorrect explanations for each question was prepared and applied to prospective science teachers. This study was carried out using case study method, one of the qualitative research approaches. The participants consisted of 30 prospective science teachers studying in 4th Grade in a state university. The data were analyzed using descriptive analysis method. The findings showed that the rate of prospective teachers who provided correct explanations in the solution of the questions about electrical circuits was high. In addition, the rate of detecting the solution steps given incorrectly was at a moderate level. It was revealed that very few participants who identified the wrong solution steps were able to make correct explanations for the solution of the question. Majority of the participants had some misconceptions such as "Generators are constant current sources", "Local reasoning" and "Regardless of how the generator and light bulbs are connected in the circuit, if the number of generators increases, the brightness of the bulb increases". These misconceptions were evaluated as an indication that prospective teachers' pedagogical content knowledge was not at a level that could be considered sufficient in terms of understanding the student. In this context, error-based activities can be included in teaching in order to prevent the formation of misconceptions, incomplete and/or incorrect information in students or prospective teachers, and to correct existing misconceptions. The effects of error-based activities on individuals' learning can be investigated in future studies.