Frozen-orbital analysis (FZOA), which has been proposed in order to analyze excitations between degenerate orbitals, is extended to the Tamm-Dancoff approximation to time-dependent density functional theory (TDDFT/TDA). FZOA for TDDFT/TDA with BLYP and B3LYP is applied to a CO molecule, and the difference between TDDFT/TDA and configuration interaction singles (CIS) is discussed.