Prospective teachers often have difficulty in posing problems. This indicates unsuccessful analogical reasoning, so prospective teachers produce non-analog problems. Therefore, a study is needed to trace the process of unsuccessful analogical reasoning of prospective teachers so that they can produce non-analog problems. The research aims to describe the analogical reasoning process of prospective teachers that causes prospective teachers to produce non-analog problems. The research method used a case study with a qualitative approach. The participating research subjects were prospective teachers from one of the universities in Sidoarjo, East Java, Indonesia. The research subjects are prospective teachers who are asked to generate analog problems but produce non-analog problems. The research instruments included analog problem posing tasks and interviews. The analogical reasoning process of prospective teachers can be traced through process components or activities in terms of retrieval, structuring, representation, mapping, application, and verification. Prospective teachers generate non-analog problems, starting with inappropriate activities in object retrieval and source problem solving. The structuring and representation of analog source objects were not successfully done by prospective teachers, resulting in non-analog problems. This impacted the next activities, namely mapping, application, and verification which were unsuccessful in producing solutions to analog target problems.