Generally, the cytotoxicity effects of nanomaterials on bio-organisms have been examined using live cells or mice by in-vivo or in-vitro testing. These methodologies, however, are time-consuming, and cell-membrane responses for cytotoxicity are often slow. Therefore, in this study, we proposed a simple testing method for colorimetric detection of dye-containing vesicles as biomimetic cell-membranes. When dye-containing vesicles are ruptured by attack of AgNPs (silver nanoparticles), dye in vesicles is released into the solution, and then the color of solution changes to that of dye. Because the ruptured vesicle causes an optical variation, we could easily and quickly monitor the vesicle rupture by AgNPs. And further, SPR (surface plasmon resonance spectroscopy) and TEM (transmission electron microscopy) analysis were carried out to confirm the vesicle rupturing. It will be provide indirect information for cytotoxicity of nanoparticles.