Recently, sintered high speed steel has attracted great attention for superior performance over that of conventional wrought high speed steel. Sintered high speed steel is also widely being used for not only cutting tools but also wear resistant parts. Two of the most popular methods of producing high speed steel are the HIP process and the billet process. In order though, to save material loss and reduce labor costs, we selected water atomized M2 class alloy powder, applying the preform process as the main part of our experiments at Hitachi Powdered Metals Co., Ltd. After numerous experiments with the above mentioned powder and process, new materials were developed with the following properties:- 1) High density of the density ratio which is now 99% or more. 2) High transverse rupture strength of 2000MN/m2. 3) High hardness of HRC 65 or more. 4) High wear resistance compared with that of conventional wrought high speed steel. 5) High pitting resistance against high stress concentration. In this paper therefore, the effect of chemical elements (C, Si, O,) on sinterability properties and the effect of the sintering temperature on mechanical properties are observed. In particular, mechanical, wear and pitting resistant properties, as the fundamental experiment, are studied in comparison with conventional wrought high speed steel.