In recent years, the analysis of biological samples has been extensively performed in pharmacokinetic and metabolic studies. The use of Secondary Ion Mass Spectrometry (SIMS) with conventional monomer ion beams, such as Ar⁺, Cs⁺ or Ga⁺, in biological applications is difficult because of the low secondary ion yield of large organic molecules and the complicated fragment ion signals. The use of cluster ions as primary projectiles in SIMS has spread dramatically in the past decade. Bismuth (Bi) cluster ions are now the most familiarized primary ions in cluster SIMS because of the high convergence property and the high molecular ion yield. Argon gas cluster ion beam (Ar-GCIB) is also one of the most attractive primary projectiles for biological application because of the soft sputtering without damage accumulation. However, our knowledge of detection limit and sensitivity is still insufficient for the practical analysis of complex biological samples with cluster SIMS. In addition, imaging mass spectrometry with high spatial resolution is crucially essential for tissue and cell analysis. In this study, lipid standard samples were measured in order to examine the detection limit and the spatial resolution of our Ar-GCIB SIMS, and the results were compared with those of the commercial Bi cluster SIMS. The results indicated that Ar-GCIB SIMS has a capability to obtain the valuable information in biological analysis, however, the improvement on spatial resolution and sensitivity is still required.