The Pd phosphine complex catalysts immobilized onto polyethylene glycol (PEG)-modified silica were prepared in order to clarify the effect of the PEG modification on the Suzuki-Miyaura coupling reaction in organic solvents. For the reaction of ethyl p-bromobenzoate and phenylboronic acid in the presence of potassium carbonate in toluene, the PEG-modified silica-immobilized Pd catalysts exhibited much higher activities than the catalysts without PEG modification.