In general, heading faces are located deep underground and isolated from main ventilation networks. Workers at heading faces are exposed to air contaminated mainly by dust and gas. Although forced auxiliary ventilation is widely employed at heading faces, it is not easy to design the optimum ventilation method. In particular the accumulation of explosive methane gas at a heading face has the potential of leading to a serious disaster. To tackle this problem, it is essential to figure out the exact nature of methane gas flow and movements in this space. This paper presents the behavior of methane gas at heading faces so as to provide information for designing adequate ventilation systems. Newly developed three-dimensional gas flow and movement software LASAR98, which is based on Computational Fluid Dynamics (CFD), was used to analyze methane gas behavior.