In recent years bonding between two steel plates was accomplished with an oil-accommodating adhesive without requiring degreasing of the steel. In this paper, the exclusion process of the oil was investigated in this adhesive on the assumption that the oil was absorbed into the adhesive layer. It was found that the oil layer essentially disappeared in the initial step of curing in which the temperature was raised to 180 degrees C, because the diffusion rate of the oil into the adhesive increased abruptly with temperature. Therefore, the bonding process in this case is not influenced by the presence of oil on the steel plates.