This paper is concerned with three dimensional solution of room air distribution by a two-equation model of turblence and the Marker-and-Cell method with second order accuracy. The analyzed flow in the first paper was laminar, and the visualized flow in the second paper was turbulent. Therefore, it is urgent necessity for practical purpose to make a numerical method of turbulent flow. The two-equation model in this paper is one in which eddy diffusivity v_t is determined from the transport equation for turbulence kinetic energy q and that for turbulence energy dissipation rate e. The analyzed room model was cubic shape with supply outlet and exhaust inlet, and was divided into 18×18×18 cells. Then, computations were carried out and steady solution could be obtained. The reulsts of computations are summed up as follows, 1) The flow patterns resemble to those of the analyzed laminar flow and the visualized turbulent flow. 2) The solutions of pressure and turbulence quantities, q, e, v_t, l do not seem to be inconsistent with authors' knowledge qualitatively. 3) The energy budget seems to balance roughly. 4) The order of pressure loss coefficient obtained from the numerical solution was almost appropriate. From the above results, this method was showed to be efficient to some extent as a predictive method of room air distribution.