:Vibration Damping Composite Steel Sheets (VDC) have recently been developed as a new material to satisfy the requirements concerning various types of noise and vibration control for various fields such as automobiles, electric appliances and building materials. Requirement for VDC continues to expand, because VDC, consisting of two steel sheets and a layer of visco-elastic synthetic resin, which is sandwiched between the two steel sheets, has an excellent damping capability. However, it is rather difficult to spot weld the VDC, as it has an electrically insulating resin layer. To improve the weldability, metal particle is generally mixed into the resin.For automotive body panels, VDC is required to have not only high vibration damping capability but also superior properties such as weldability, bonding strength and formability.In this study, the effects of metal particle size and volume fraction on these properties have been investigated. Furthermore, a nugget formation behaviour of the developed VDC and relationship between welded joint strength and nugget structure have been studied in detail. It is found that the conductible type VDC which satisfies these properties can be made from the resin containing iron particles and a step current welding method assures adequate welded joint strength.