In this study, we employed laser ablation/inductively coupled plasma mass spectrometry (LA-ICP-MS) to map the spatial distribution of Gd-doped iron oxide nanoparticles (IONPs) in one tumor slice that had been subjected to magnetic fluid hyperthermia (MFH). The mapping results revealed the high resolution of the elemental analysis, with the distribution of Gd atoms highly correlated with that of the Fe atoms. The spatial distributions of C, P, S, and Zn atoms revealed that the effect of MFH treatment was significantly dependent on the diffusion of the magnetic fluid in the tissue. An observed enrichment of Cu atoms after MFH treatment was probably due to inflammation in the tumor. The abnormal distribution of Ni atoms suggests a probable biochemical reaction in the tumor. Therefore, this LA-ICP-MS mapping technique can provide novel information regarding the spatial distribution of elements in tumors after cancer therapy.