Iron implanted silicon wafers and a stainless steel film were analyzed by PIXE using a few MeV Ni 3 + , Si 3 + and proton microprobes. The X-ray spectra showed that the X-ray emission strongly depended on the incident ion species. It shows that the Si probe has a sensitivity to the Fe-L line higher than that of the proton probe. On the other hand, the proton probe has sensitivity to the Fe-K line higher than that of the Si probe. Using a Ni probe, both Fe-L and Fe-K lines could be observed simultaneously. The Ni probe has higher sensitivity for both X-ray lines than the other probes. Furthermore, the background level in the region of the Fe-K α line is much lower than in the case of the proton probe. It is considered that molecular orbital effects took place between Fe and Ni atoms due to very close level matching. The energy shift and broadening due to multiple-ionization were observed in the X-ray spectra of the Si and Ni impacts.