This paper deals with dynamic behavior of steel moment resisting frame incorporated with lead damper into beam splice, for the purpose of establishing damage free structural system against severe earthquakes. An experiment using full scale beam-column subassemblage has been conducted to verify the proposed system under dynamic loading conditions. The subassemblage as well as the lead damper, subjected to sinusoidal and random excitations, has exhibited stable load-deflection relation, and does not remarkably deteriorate even in the reversed loadings of 140 cycles. Then, the proposed system has been successfully verified to reach the goal of establishing damage free structure.