We investigate two-dimensional laminar flow around rectangular cylinders placed in a uniform stream. Numerical simulations are performed, using finite volume method, in the ranges of $50{leq}Re{leq}150$ and $0.1{leq}W/H{leq}1.0$, where Re and W/H are the Reynolds number and the width-to-height ratio, respectively. The immersed boundary method is used to handle the rectangular cylinder in a rectangular grid system. Comparisons with the previous results show good agreement in Strouhal number, drag and lift coefficient. The present study reports the detailed information of flow structure at different width-to-height ratios in the ranges of $50{leq}Re{leq}150$.