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To improve cooling effectiveness of film-cooling hole, bending of hole was investigated and optimized using surrogate modelling based on three-dimensional Reynolds-averaged Navier-Stokes analysis. The turbulence was modeled using a shear stress transport model. The spatially-averaged film-cooling effectiveness was employed as the objective function, and the injection angles of the lower and upper cylindrical parts and height of the bending point were selected as design variables for optimization. The Kriging model was used to approximate the objective function. 27 design points were selected by the Latin hypercube sampling, where objective function values were calculated to construct the surrogate models. The results at a blowing ratio of 0.5 showed that the optimum bended film-cooling hole improved the spatially-averaged film-cooling effectiveness by 39.9 % and 78.0 % compared to a reference bended hole and a cylindrical hole, respectively.