Error propagation of buffer analysis in a vector-based geographical information system (GIS) is studied with the use of statistics and numerical analyses. In this paper, such factors as the error of commission, the error of omission, the discrepant area and the normalized discrepant area are proposed as the error indicators of buffer analysis. Analytical expressions for the error indicators are developed as multiple integrals. A numerical integration method is recommended to find an approximation to the analytical expression.