An experimental study has been made on the friction reduction of a model ship for a bulk carrier by means of air lubrication. We designed two types of devices to keep the supplied air in the hollow of the flat bottom of the model. For the even trim condition the air sheet is very robust and the maximum friction reduction is about 30%. The air supply requires energy by 5.4% of that for propulsion while its decrease due to the air lubrication is 20.1%. Therefore, 14.7% of the propulsion energy is saved for the model ship. However, different patterns of air separation, which deteriorate the effect of air lubrication, were observed for the positive and negative trim conditions, respectively. It is considered that these patterns are attributed to the distribution of flow pressure on the bottom of the model.