Abstract: Apparatus for purifying exhaust gas from a diesel engine includes a wall-flow filter made of a porous ceramic material for capturing carbon components contained in the exhaust gas and burning up the captured carbon components, a first exhaust pipe for introducing the exhaust gas into the filter, a second exhaust pipe for introducing the exhaust gas purified by the filter a bypass pipe bypassing the filter, first and second valves arranged inside of the first and bypass pipes, respectively, for controlling the exhaust gas flow, a heater for burning up carbon components captured in the filter, first and second temperature sensors for detecting temperatures in the first pipe and the filter, respectively, and a controller for controlling opening and closing of the first and second valves based on the temperature difference between temperatures detected by first and second temperature sensors to prevent the filter from cracking.