Many human diseases have been reported to be associated with mitochondrial dysfunction. Therefore, mitochondrial therapy would be expected to be useful and productive in the treatment of various diseases. To achieve such an innovative therapy, it will be necessary to deliver therapeutic agents into mitochondria. However, only a limited number of methods are available for accomplishing this. We previously developed the MITO-Porter, a liposome-based carrier that permits macromolecular cargos to be transported into mitochondria via membrane fusion. Intracellular observations using the green fluorescence protein as a model macromolecule confirmed the mitochondrial delivery of a macromolecule by the MITO-Porter. Moreover, when we attempted the mitochondrial delivery of bongkrekic acid (BKA), an antiapoptosis agent, the MITO-Porter enhanced the antiapoptosis effect compared with naked BKA. To construct a device with enhanced performance, the MITO-Porter was coated with cell membrane-fusogenic outer envelopes to produce the dual function (DF)-MITO-Porter. Intracellular observations indicated that the DF-MITO-Porter was more effective in delivering exogenous macromolecules into mitochondria than the conventional MITO-Porter. Furthermore, when biomacromolecules were delivered using the DF-MITO-Porter to estimate the mitochondrial gene targeting of the carrier, the results confirmed that the MITO-Porter system has the potential for use in therapies aimed at mitochondrial DNA. This paper sumarizes our findings on mitochondrial drug delivery systems that are directed toward mitochondrial medicine development and mitochondrial gene therapy. It is expected that the MITO-Porter system will open new research areas in mitochondrial drug delivery systems and have a significant impact on the medical and life sciences.