Work on the reduction of particulate matter from a Diesel engine has led to a new trap and a method of controlling the combustion rate of the particulate matter filtered in the trap. Ceramic cordierite is a major component of the trap and is susceptible to thermal shock. Thus, techniques were tried to reduce the peak temperature and temperature gradients in the ceramic filter because these were assumed to be the main factors causing thermal shock of the ceramic filter during regeneration. Temperatures were measured inside the filter during regeneration; the oxygen concentration at the outlet of the filter was also measured, to investigate the combustion characteristics of the particulate matter. The temperature distributions and temperature gradients in the filter during regeneration varied widely according to the regeneration control scheme. It was found that intermittent combustion of the particulate matter assured relatively desirable temperature characteristics for durability of the ceramic filter. In addition, modification of the technique resulted in efficient regeneration of the trap.