Aromaticity reversal in the lowest triplet state, or Baird’s rule, one of the most interesting concepts in the field of physical organic chemistry, has been postulated for the past few decades with the aid of theory and quantum calculations. Despite of numerous theoretical works on aromaticity reversal, experimental study for aromaticity reversal is still in the rudimentary stage. Thus, here, we have investigated the aromaticity reversal in the lowest excited triplet state using a comparable set of [26]- and [28]hexaphyrins by femtosecond time-resolved infrared (IR) spectroscopy. Compared to the relatively simple IR spectra of [26]bis-rhodium hexaphyrin (R26H), those of [28]bis-rhodium hexaphyrin (R28H) show complex IR spectra in 1300-1700 cm-1 where the stretching modes of conjugated ring can be detected. On the other hand, the time-resolved IR spectra of R26H in the excited triplet state are dominated by an appearance of excited state IR absorption peaks, while those of R28H are largely composed of ground state IR bleaching peaks, which reflects the aromaticity reversal in the lowest triplet state as illustrated by the structural changes. Therefore, these contrasting IR spectral features with quantum mechanical calculations would serve as new experimental aromaticity indices showing Baird’s rule.