Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has become a powerful tool to analyze surface chemical structures of organic materials. In this study, TOF-SIMS imaging and quantitative analysis were done with two immiscible polymer alloys : polystyrene (PS)/ethylene/ vinyl acetate (EVA) and nylon-6/poly phenylene ether (PPE). It was confirmed that TOF-SIMS imaging technique could be used to identify the micro chemical structure of polymer alloys. In the surface quantitative analysis of these polymer alloys, however, the surface compositions calculated from the characteristic fragment ion intensities varied to a large extent. The maximum scattering of data occurred at near the composition of 1 : 1. The scattering might be caused by differential charging on the polymer surfaces.