In order to investigate the influence of surface roughness on load dependence of microhardness of annealed structural rolled steel and carbon steel, hardness tests were made by changing the grade of surface roughness as a parameter. The results obtained were analyzed by means of the analysis of variance.The main results obtained were as follows;(1) Load dependence existed between the indentation load and the microhardness number above the specified value of hardness. The range of the indentation load showing load dependence was influenced by the surface roughness.(2) A logarithmic linear relationship existed between the indentation load and the microhardness number. Load dependence curves varied depending upon the surface roughness.