Quark mass matrices on a minimal parameter basis

General features of three-family quark mass matrices $M_u$ and $M_d$ on a specific quark basis are discussed. This quark basis is defined as the basis on which a traceless matrix $\mathrm{iK}\equiv M_u{M}_d-M_d{M}_u$ takes a diagonal form. In this mass matrix scheme, the number of independent parameters in $M_u$ and $M_d$ is the same as that of the observable quantities, i.e., ten parameters.