Hardness is influenced by mechanical properties of a spherical indenter in the elastic-plastic transient indenting process. To clarify that point, we indented steel and tungsten carbide spherical indenters into several standard blocks for hardness. In order to experimentally establish the relations of the elastic-plastic transient indenting process. we related the hardness Pm (mean contact pressure) with the true profile coefficient of a permanent indentation (d/Dp), not with an apparent profile coefficient (d/D) used traditionally, and formulated as follows; P_m=P_up(d/D_p)^xp We can calculate the hardness affected by the different mechanical properties of the spherical indenter using this formula for arbitrary conditions. Further, we compared the Brinell hardness obtained by Yoshizawa with our calculated values, and found good coincidence between them.