The object of this work is to analyze the dynamic characteristics of the portal closed frame which consists of two stepped beams including a torsional spring at the discontinuous point and a rigid body connecting each beam tips. This system is available in a lot of cases that need higher stiffness and linear motion of the tip mass. For example, it might be used for an optical pick-up actuator, using piezoelectric materials, of the high areal density CD, DVD or the next generation of optical memory devices, which requires super rigidity and linear motion in focusing. The mathematical modeling and the derivation of the equation of motion are given for the beam that is identically paralleled and stepped cantilevers. The equation of motion and the associated boundary and the continuous conditions are analytically obtained by using variational Hamilton’s principle. The exact solutions are presented and compared with the results obtained by the use of the FEM Tool (IDEAS).