Flow field and aerodynamic performance of the Mars airplane with a complete aircraft configuration are analyzed by RANS simulations. At the Reynolds number of 3.3x10⁴, a flow field is solved by an unstructured three-dimensional compressible CFD solver (LS-FLOW). Here, the Mars airplane is assumed to have the Ishii airfoil as the main wing shape. The Ishii airfoil is known as its good performance at the low Reynolds number condition. An objective of the present study is to clarify flow structures around a complete aircraft, for optimization of design of the Mars airplane. The results show that the features of the aerodynamic coefficients correspond to those of experimental results and the contribution of the main wing is significant on the aerodynamic characteristics of the entire airplane.