In the automotive field, safety has become a worldwide issue along with energy and the environment. In an effort to propose a shock isolator based on a new principle, the authors have formulated an idea of isolating and reducing shock by transforming rectilinear motion into circular motion. We call it a swinging unit. According to its principle, it is a shock isolator, not absorber. In this report, we described this transformation of motion and give an analysis of the fundamental characteristics of the swinging unit.One of the main components of the swinging unit is a disc which rotates around a pin. This pin is inserted through the disc at a point distant from the center of the disc by an eccentric radius e. Our experimental results showed the unit is effective in reducing shock and an eccentric radius is a dominant factor in this shock reduction.