The response of zeta potential,ζ_obs, to membrane surface condition and surfactants in solution was investigated from the viewpoint of the interaction between surfactant and membrane surface. The ζ_obs of three polyvinylidene difluoride (PVDF) microfiltration membranes, which had non-ionic hydrophilic, hydrophobic, and positively charged pore surfaces, with nominal pore size of 0.22 μm were measured over wide range of the surfactants concentration. N-Dodecyltrimethyl ammonium chloride (DTAC) and Sodium Dodecyl Sulfate (SDS) were used as cationic and anionic surfactants, respectively. At the lower surfactant concentration (the conductivity below 20mS/m) the behaviors of ζ_obs mainly depended on the combination of membrane and surfactant used and they can be explained by the interaction between surfactant and pore surface. At the higher surfactant concentration the behaviors of ζ_obs mainly depended on type of surfactant rather than on membrane used. In the case of SDS the severe flux decline was observed at a certain concentration in all the membranes and the absolute value of ζ_obs decreased and approached to zero reflecting the flux decline.