The S-1 <-- S-0 excitation spectra of m-tolunitrile and its 1:1 complexes with Ne, Ar, and Kr were measured under the supersonic jet condition by the laser-induced-fluorescence and hole-burning techniques. The torsional potentials for the internal rotation of the methyl group in the S-1 state were determined from the observed torsional frequencies. The effect of the complex formation on the torsional potential is discussed.