Dispersion conditions of exhaust gas emitted from the ship stack are varied due to the state of sea surface, ship velocity and external environment condition etc. In the certain circumstances, the exhaust gas flowing backward phenomena is appeared due to the shape of vessel structure. The negative pressure layers can appear at the rear part of deck house and cause the exhaust gas flowing backward phenomena. In this study, 1:100 scale model ship was manufactured and tested in the large wind tunnel test center to ensure the exhaust gas flow patterns. Measurement results showed that the greatest pressure point was x/H=1.55 at zone 6 and Case 2 was a relatively high wind pressure distribution.