Cycloparaphenylenes (CPPs) are hoop-shaped conjugated hydrocarbons corresponding to partial structures of fullerenes or armchair carbon nanotubes. Here, we examined the fluorescence properties of a series of [n]cycloparaphenylene dications ([n]CPP2+, n = 5-9), which have unique in-plane aromaticity. The fluorescence peak positions of the [n]CPP(2+)s shifted to the longer-wavelength region with increasing ring size, reaching the near-infrared region for those with n > 5. The fluorescence quantum yield of [6]CPP2+ was the highest among the [n]CPP(2+)s examined in this study, and the value was on the same order as that of carbon nanotubes. The Stokes shifts of [n]CPP(2+)s were smaller than those of neutral [n]CPPs, which do not have in-plane aromaticity. Theoretical calculations indicate that [n]CPP(2+)s undergo smaller structural changes upon S-0-S-1 transition than [n]CPPs do, and this is responsible for the difference of the Stokes shift. Furthermore, molecular orbital analysis reveals that the S-0-S-1 transition of smaller [n]CPP(2+)s has an electric-dipole-forbidden character due to HOMO -> LUMO/HOMO -> LUMO+1 mixing. The relatively high fluorescence quantum yield of [6]CPP2+ is considered to arise from the balance between relatively allowed character and the dominant effect of energy gap.