Fully 3-dimensional model for Monte-Carlo simulation code (DEGAS) was newly applied in the GAMMA 10 central cell. Based on the measurement and DEGAS simulation, neutral transport during the gas puffing and neutral beam injection (NBI) in the central cell is investigated. The predicted H profile using DEGAS well explained the experimental result. It is clarified that the localized neutral source has much influence on the behavior of neutral particles in the plasma. In this paper, detailed discussion is shown from the view point of both the experiment and the simulation.