Using an ion-photon merged-beam apparatus, photoion yield spectra of Cs²⁺ and Cs³⁺ from the 4d photoionization of Cs⁺ have been measured as a function of photon energy in the range 80-140 eV. Above 90 eV, the 4d giant resonance peak is observed clearly for Cs³⁺ spectrum. Below 90 eV, some prominent discrete peaks are observed for both Cs²⁺ and Cs³⁺. These discrete peaks can be attributed to the 4d-np and 4d-nf transitions.