We propose a new scan matching algorithm that makes use of the simple polygonal structure of environment. Our method extracts line segments from a current scan and matches them with line segments in a previous scan, that is, tracks the line segments in the sequence of scan. Our method simultaneously computes the pose shift (Δx ,Δy,Δθ) based on the correspondence between line segments in the two successive scans and the transformation such that the current scan is mapped optimally to the previous scan. By the use of line segments in the scan, it is possible to detect invariants for position and orientation estimation in the environment. First of all, we explain the algorithm of our method, and then report the experimental result in order o show the effectiveness of our method.