The poor lubricity of diesel fuel in the distributor type injection pumps of diesel engines that use the diesel for lubrication of their moving parts has been caused by the reductions of sulfur content in the diesel fuel. The wear scar diameters by HFRR (High Frequency Reciprocating Rig) were measured on the diesel fuels from Korean markets and the results were compared with their physical and chemical properties to investigate the reason for poor lubricity of low sulfur diesel fuels. As a result, it was found that the lubricity of the injection pumps has been affected by the polar heterocyclic compounds. Therefore, it is suggested that the factors affecting the lubricity stated above should be taken into account to improve the lubricity property of diesel fuel in the refining process.