Objectives: The study investigated the links between workplace measures implemented in response to COVID-19 with mental health and work performance of employees in Japan. Methods: This was a cross-sectional study of a sample from a cohort study of full-time employees. Participants (n = 1448) completed an online self-report questionnaire on March 19-22, 2020. Multiple linear regression was conducted to ascertain their fear of and worry associated with COVID-19, psychological distress, and work performance. Results: The number of workplace measures correlated positively with respondents' fear of and worry associated with COVID-19 (adjusted standardized β = 0.123, P <.001), negatively with psychological distress and positively with work performance (adjusted standardized β = −0.068, P =.032; adjusted standardized β = 0.101, P =.002; respectively). Conclusions: Workplace measures may promote and maintain the mental health and work performance of employees during the COVID-19 epidemic. The positive association between the number of measures and fear and worry about COVID-19 may reflect increased awareness about COVID-19 among employees resulted from taking the measures.