In aerodynamic geometry optimization using global optimization methods such as evolutionary algorithm, the computational body-fitted grid formation in the computational fluid dynamics is a bottleneck in terms of efficiency and accuracy. In this presentation, an overview of a method to evaluate aerodynamics by computational fluid dynamics based on the immersed boundary method, which enables the calculation of flowfields for arbitrary shapes based on an orthogonal mesh instead of a body fitted mesh along with the object, will be presented and prospects will be discussed.