The objective of this paper is to describe the performance of an impulse turbine with fixed guide vanes and to compare it with that of the Wells turbine with guide vanes. As a result, a suitable choice of the design factors for the impulse turbine was shown for the inlet angle of rotor blade and the shape of guide vane. Further, it was found that the running and starting characteristics of the impulse turbine were superior to those of the Wells turbine under irregular wave conditions.The objective of this paper is to describe the performance of an impulse turbine with fixed guide vanes and to compare it with that of the Wells turbine with guide vanes. As a result, a suitable choice of the design factors for the impulse turbine was shown for the inlet angle of rotor blade and the shape of guide vane. Further, it was found that the running and starting characteristics of the impulse turbine were superior to those of the Wells turbine under irregular wave conditions.