Although population ageing is progressing, seniors migrate with increasing frequency. This paper explores the question why Polish pensioners decide to migrate, as existing research has not provided satisfactory explanations. Reasons for migrations were determined on the basis of pensioners' answers to a questionnaire survey. The results show that migration decisions are taken for a number of reasons, which depend, inter alia, on the respondents' education level, age, and sex. For women as well as for men, the economic aspect plays a crucial role (e.g., building or buying a new house). Ward's method was employed to distinguish five main migration types according to the main motivating factor; that is, family and finance, family, environmental, economic, and health. An analysis of internal as well as external migrations of Polish seniors shows that they differ considerably from migrations of seniors in other countries. Due to their unsatisfactory finances as well as deficits in knowledge of foreign languages, Polish pensioners, unlike their peers in other countries, rarely decide to settle down abroad. The Polish model of multigenerational family in which seniors assist their children in raising their grandchildren also contributes to lower emigration.