This paper presents the outline of a theoretical analysis of bending and torsional vibration of passenger car bodies. Body structure is simulated by a framework with tension rigs and additional panel stiffnesses. The framework is a three-dimensional model for the bending and torsional vibration, or two-dimensional for the bending vibration, and is analyzed by the lumped mass system. All input data are calculated from drawings, and therefore characteristics of body structure are forecast and controlled in the design process. The analysis is also applicable to coupled vibration and forced vibration problems.