The influences of direction of fuel injection and the temperature of the combustion chamber wall upon the ignition and the combustion process in the swirl chamber of a Diesel engine were investigated by means of high-speed photographs with indicator diagrams synchronized. The summary of results are as follows : (1) Ignition of fuel is delayed by the cooling effect of the wall when the wall temperature is low, and this trend grows more remarkable as the direction of injection gets nearer to the wall. (2) Duration of combustion is prolonged by increasing the concentration of fuel particles in the middle part of the chamber and by shortening the delay as well as by the increase of fuel adhering to the wall, which mitigates the rate of pressure rise due to combustion. (3) When the fuel is injected along the wall, several features of combustion such as blue flame combustion, ignition from several positions and an abnormal shortening of the ignition delay were observed.