Quasi-spherical diamond crystals having an average diameter of 3.7±0.6 nm are attracting much attention as an ideal material in carbon nanotechnology. In contrast to the other popular nanocarbons including fullerenes, carbon nanotubes and graphenes, our single-nanodiamond can be produced in uniform shape/size on industrial scale. Thus, the most serious problem in nanocarbon industry that persisted in the past 25 years, namely the technical failure to produce highly crystalline nanocarbons in narrow shape/size range does not exist in our diamond from the beginning. Among potential applications of the single-nanodiamond under development, this review concentrates on its highly promising role as a drug carrier, especially for therapeutic-resistant cancer. An interesting possibility of intercalation is proposed as the mechanism of drug transport through blood, which takes into accounts of the spontaneous formation of nanographene layer on the  facets, which is then extensively oxidized during oxidative soot removal process to give nanographene oxide partial surface, capable of intercalating drug molecules to prevent them from leaking and causing undesirable side effects during transportation to target malignant cells. A perspective of quantifying the drug delivery process by anticipating orders of magnitude in the number of administered detonation nanodiamond (DND) particles is suggested.