We have found capsule-formed dimers of polycyclic aromatic hydrocarbons (cap-di-PAH) for coronene, ovalene, and circumcoronene by quantum chemical calculations. Two monomers are connected at the edge that gives a capsule form, holding the aromatic characters in the inner six-membered rings. The aromatic pi-electron networks at the upper and lower parts of the dimers are not merged each other. Those cap-di-PAHs are located in sufficiently deep potential wells surrounded by high energy barriers, indicating the high possibility of existence.