For the next leap in the power technologies to get the sustainable society, we are under obligations not only to cope with the warming global environment but also to conserve the natural ecosystem and coexist with the nature. Wave energy which is one of the renewable energy attracts attention as a promising resource that can reduce CO2 emission. In the optimum design of a fixed oscillating water column (OWC) type wave energy converter, it is necessary to develop a design method which can consider the characteristics of incident wave motion, the motion of the internal free surface affected in the structure such as a partly submerged wall, the fluctuation of air pressure in an air chamber, the rotation of the air turbine. In this paper, the 2-D wave tank tests for the fixed OWC type wave energy converter with an impulse turbine were conducted to obtain the experimental data needed to make this design method. Firstly, steady air flow tests for a single impulse turbine with guide vanes were performed to grasp the characteristics of the turbine without the effect of water waves. Secondly, the oscillating air flow tests by water waves were carried out to obtain the performance of the OWC with the same impulse turbine. As the results, the effects of the water depth and the air chamber length on the generating efficiency corresponding to product of the primary and secondary conversion efficiencies are clarified.