Wall recycling and results of ICRH discharge in the HANBIT mirror device are presented. The amount of gas loading due to recycling from the wall and recycling coefficient are estimated quantitatively by the time evolution of the pressures in each region of the HANBIT mirror device during plasma discharges. These measured pressures are compared with a model calculation made in terms of a coupled set of rate equations. Also we introduce a gas recycling model based on atomic and molecular processes. In this model, enhancement of fueling due to the recycling is evaluated on the basis of the calculated probabilities of neutral and ion production by using the rate coefficients of these reactions.