To investigate the physiological roles or toxicity of trace or toxic elements, multielement analysis of limited quantities of samples in the biological tissues is required. Inductively coupled plasma mass spectrometry (ICP-MS) suits this requirement, but spectral and nonspectral interferences are inevitable. We examined correction methods for the nonspectral interferences by analyzing signals of 21 elements in various concentrations of HNO3 as well as five major elements (Na, K, P, Ca, and Cl). Using internal standards, the interferences caused by the major elements were corrected, but the interferences caused by HNO3 were impossible to correct for elements with high ionization potentials. The analytical results using the standard addition method on 14 elements in standard reference materials and fresh brain tissues confirmed the accuracy of this method. Thus, we concluded that the standard addition method is useful to correct for the nonspectral interferences.