Research on the motives behind a university professor’s decision to retire is scarce. In the present work, we have tried to define and delimit the aspects of the university professor’s satisfaction that have an influence on their motivation to retire. Nine hundred and one Spanish university professors answered the Inventory “Questionnaire for Active, Retired and Emeritus University Professors.” In the analysis, three structural equations were estimated. The overall sample, as well as the professional status subsamples—active or not active—were taken into account. Significant differences were found according to the work status. Three dimensions explained the satisfaction: economic, professional, and relational. The satisfaction of the professors in each of them had an influence on their decision to retire. Work conditions created by the European Higher Education Area (EHEA) and work conditions due to the educational and/or university laws determined the economic satisfaction to a greater degree. The possibilities of being part of professional networks or teams, and of publishing and disseminating knowledge, have a considerable impact on professional satisfaction. Relational satisfaction was notable for predicting the motivation to retire. Relationships with colleagues had an effect on the relational satisfaction. Policies for improving the satisfaction of the university professors could help delay the exit of talented professors, who are part of the human capital of the universities.