A steam turbine rotor shaft and a method of manufacturing the same are provided wherein the sliding characteristics of a journal are improved, and the journal is free from welding cracks and does not need a post heat treatment. The low alloy steel coating layer having a better sliding characteristics than 9 to 13% Cr heat resisting steel and a area rate of defects including pores and oxides in a range of 3 to 15% is formed by a high velocity flame spray coating method on a sliding surface of the journal.