The aerodynamic characteristics of tandem cables of cable-stayed bridges has become more and more serious problem with increment of span length. From the view point of reduction of construction cost and maintenance of cable, tandem cables have been adopted for cablestayed bridge. The tandem cables however, have aerodynamic response characteristics like wake-galloping. Therefore, it is required to develop the method for suppressing wake-galloping of tandem cables. The purpose of this study is to grasp the characteristics of wake galloping phenomenon on tandem cables of cable-stayed bridge using the numerical fluid flow analysis. The flow around the fixed tandem circular cylinders modeled for tandem cables is calculated varying the angle of tandem cylinders. Flow field is treated as incompressible viscous flow, and the selective lumping three-step explicit finite element method which is based on the sound speed method is adopted for the discretization method.