It is important to evaluate the internal energy of the sputtered neutral particles to optimize their resonant ionization efficiency. In this study, the internal energy of the sputtered Al atom, especially the ground state P-2(1/2) and the lowest-lying excited state P-2(3/2) (112 cm(-1)), was monitored by using resonant laser postionization sputtered neutral mass spectrometry. The results of the authors showed the density of the ground state of the sputtered Al atom drastically decreased due to surface oxidation, as well as the enhancement of the secondary Al+ yield.