Abstract: Provided is a structure with which a lung progenitor cells can proliferate while retaining an ability to differentiate into an alveolar epithelial cell and an airway epithelial cell. A structure of the present invention includes a core portion that includes a cell population, and an outer shell portion that covers at least a part of the core portion and contains a hydrogel. The structure has a storage elastic modulus of 150 Pa or more and/or the hydrogel contains alginic acid. The cell population contains an alveolar epithelial cell, an airway epithelial cell, and/or a progenitor cell thereof.