Ethical values and performance have gained importance in the Korean public sector because of the new public management wave and social issues such as corruption. This study examines how the effects of types of organizational culture, such as performance-driven culture and ethics-driven culture, serve as the antecedents of public service motivation (PSM) among central government agencies, public enterprises, and executive agencies in Korea. Furthermore, it investigates how trust in top management affects PSM and how organizational culture moderates this relationship. A survey of 1,216 Korean public employees and seven focus group interviews show that trust in management strongly predicts PSM. Performance-driven culture is positively and significantly associated with norm-based PSM and affective PSM, and ethics-driven culture predicts rational PSM. The moderating effects of organizational culture differ by PSM dimension.