Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been widely adopted for the direct multi-elemental analysis with high sensitivity. Especially analysis of flne ceramics by LA-ICP-MS without time-consuming sample decomposition process has been one of the most expecting application fleld. Small additive elements in MgO powders were analyzed by LA-ICP-MS. For precise and accurate analysis in∞uence of carrier gas (Ar or He) was presented by the signal intensities of ICP-MS, relative standard deviation of signal intensities and ablated particle size distribution. Ablated particles were collected and analyzed by scanning electron microscopy (SEM) to investigate the particle size distribution, and the ablated sample surface was examined by camscope. In He gas atmosphere, the signal was more stable than in Ar gas atmosphere. The signal intensity was higher in Ar than in He. Examination of ablated particles and sample surface reveals that more particles were generated in Ar atmosphere and the distribution of particle size was larger.