We have investigated using partial oxidation of an Si wire for forming quantum dots. Calculated results show oxidation induced strain leads to the formation of effective quantum dots, although actual dot-shaped structures are not formed. By investigating formation conditions, we have found that partial oxidation of an Si wire on a (001) substrate is very efficient for the formation of oxidation-induced effective quantum dots. Moreover, our calculated results are qualitatively consistent with experimental results obtained with our Si single-electron transistors (Si-SET) fabricated by pattern-dependent oxidation (PADOX).