The structure of toluene dimer generated in a supersonic jet has been investigeted by hole-burning and stimulated Raman-UV double resonance spectroscopies. Hole-burning spectroscopy revealed that the broad electronic spectrum of the S₁-S₀ transition of the toluene dimer consistes of two components due to two isomers at least. On the basis of the calculated result given by Schauer and Bernstein, the two isomers were attributed to a sandwich-shaped dimer and a T-shaped dimer, respectively. Accurate vibrational frequencies of three vibrations ν₁, ν₁₂, and ν_18a for toluene-h₈, toluene-d₈, and the dimer were obtained by stimulated Raman-UV double resonance spectroscopy. It was found that the 12₁ level of bare toluene-h₈ is perturbed by the vibration involving methyl rotation and its perturbation is reduced upon the dimer formation.