For the study of so‐called 4d giant resonance of an Xe atom and its iso‐electronic sequence, the linear response method with the density functional theory is applied. Particular attention is made for the 4d photoexcitation process of Xe together with the continuum spectrum and the excitation peaks in the experiment are identified for the first time. Systematic study for iso‐electronic sequence of Xe‐like ions and atoms, i.e., I−, Xe, Cs+, Ba++ and La3+ are reported in order to see the role of the dynamic electron correlation to 4d‐photoexcitation/ionization processes.