A hierarchical Cartesian-grid-based flow solver which have the capability to model the turbulent boundary layer using immersed boundary method with a wall function is used to investigate the flow around a realistic landing gear model developed by Japan Aerospace Exploration Agency. The calculations are performed on three different grid resolutions to understand the grid dependencies. The cell number of the finest case is around 82 million, and the statistical data is obtained within two days including grid generation. The overall flow field around the complex geometry is investigated in detail based on the time-averaged flow field. The results show favorable agreement with the experimental data.