The change of the electronic structure as well as the hybridization between the localized 4f state and the conduction band (cf hybridization) of Ce_1-xLa_xPd₃ (x = 0, 0.03) due to the La-substitution has been studied by the optical conductivity spectra in the infrared region. The width of the optical transition of Pd 4d \rightarrow Ce 4f states that was mainly observed in the energy region shrinks by the La-substitution. This means that the cf hybridization is strongly suppressed by the absence of the periodicity of the Ce-ion.

PACS numbers: 71.27.+a, 78.20.Ls, 75.30.Kz