Slow light propagation in solid state material is initially observed at room temperature. The slowdown of light resulting from dramatic change of refractive index by spectra hole which is produced by coherent population oscillation is investigated in a ruby crystal at 514.5 nm from Ar+ laser. Measured delay is about (2.314±0.005) ms, corresponding to group velocity as low as (43.215±0.094) m/s. The variation of the delay and the group velocity with modulation frequencies is observed in the experiment.