Buildings in seismic areas are being vulnerable to strong ground accelerations during the times of ground shaking, which results in the occurrence of severe base shear and acceleration in the structure. As a remedy, passive devices (Base Isolators) were introduced to diminish the seismic energy transferred to the building but the isolators are found to be severally damaged during the near fault seismic excitations and are also exposed to large displacements. Therefore, after the post-earthquake the isolator’s working conditions becomes critical. Hence to overcome those limitations a novel passive device named “Negative Stiffness Device (NSD)” has been introduce to impart apparent weakening the structure at the level of deployment of the device. A Pre-compressed spring, pivot plate, lever arm, two chevron braces and gap spring assembly are the components of the device. In the current study a G + 3 Reinforced Concrete (R.C) frame bare building which is situated in zone-III has been considered for the analysis and a Non-Linear Time History Analysis has been carried out to access the seismic response reduction of the structure with the implementation of NSD at various storey heights. From the results observed, the NSD is found to be efficient in mitigating the structure’s earthquake responses. The building’s base shear and acceleration are diminished about (30–45) % and (15–30) % respectively.