We review a recently developed ab initio multireference (MR)density functional theory (DFT) approach based on the partially interacting reference systems. Instead of Kohn-Sham equations, we introduce the auxiliary Cl equation with the effective DFT potential field. For practice, we classify electrons of the target system into valence electrons and other electrons. The former plays the quantum resonating feature of electronic structure of molecular species, while the latter affects the electronic properties via the effective correlation potential for the former electrons. The theoretical devices in our MR-DFT are introduced to avoid the double counting problem for any combination of a wavefunction and a correlation functional. Some numerical examples are presented.