Femtosecond time-resolved photoinduced reflectance change was measured on a spin-coated dye (cresyl violet) of submonolayer coverage (4 x 10(13) cm(-2)) on a fused silica substrate. We found that the sensitivity of the reflection measurement was much higher than that of the absorption measurement for thin monolayers of dye. A prominent beating structure due to vibrational coherence of the dye was observed on the time-resolved reflection signal. A vibrational spectrum of the dye at submonolayer coverage, which corresponded to its resonance Raman spectrum, was obtained in the range 0-800 cm(-1) by a Fourier transform analysis of the reflection signal.