Fe L-2,L-3-edge x-ray absorption spectra (XAS) and magnetic circular dichroism (MCD) in resonant inelastic x-ray scattering (RIXS) of alpha-Fe2O3 were measured to identify the electronic structure responsible for its weak ferromagnetism caused by the Dzyaloshinskii-Moriya interaction (DMI) at room temperature. In contrast to negligible MCD in XAS, MCD in RIXS (RIXS-MCD) was clearly observed in the dd excitation at 1.8 eV via excitation to charge-transfer states. Furthermore, RIXS-MCD showed a crystal orientation dependence, indicating that the observed RIXS-MCD originated from DMI. The observed RIXS-MCD is well described by ab initio charge-transfer multiplet calculations, revealing that the RIXS-MCD derives from spin flip excitations at delocalized e(g) orbitals. By the combination of the experiments and calculations, RIXS-MCD has unraveled that the origin of DMI in alpha-Fe2O3 is the e(g) orbitals, which are strongly hybridized with the 2p orbitals of oxygen atoms. The results demonstrate the importance of RIXS-MCD for identifying the electronic structure related to DMI.