This study demonstrates that corporate philanthropy (CP) has dual attributes by theorizing and testing the existence of rational CP and irrational CP and their opposite effects on firm value. The empirical results show that rational CP has a positive effect on firm value, while irrational CP has a negative effect on firm value. Further analysis shows that the negative effect of irrational CP on firm value is stronger in firms with corporate foundations and in state-owned firms. The findings can coordinate the theoretical contradiction and empirical divergence between the efficiency view and the agency view existing in the current research.