Softly broken supersymmetric theories

Mass independent renormalization scheme is introduced for broken supersymmetric theories. As far as the breaking is soft, the explicit breaking of supersymmetry does not spoil the cancellation of quadratic divergences (in self-energies of spinless particles) which is useful in building unified gauge models with the ''naturalness'' of 't Hooft and Veltman. Renormalization of broken supersymmetric Ward-Takahashi identities is also discussed. (author)