The new concept catalyst for diesel engine has been developed. When the exhaust temperature is low, SOF and HC are temporarily adsorbed by the adsorbent within the catalyst and are oxidized as the temperature rise. The process of this development have manifested as follows. (1) The coating material is important factor to govern the oxidation activity. (2) SOF is reduced by the coating material in low temperature less than 200degC. (3) The coating material, which has low SO2 adsorbing rate suppress the sulfate formation at high temperature. 2 refs., 11 figs., 1 tab.