In the present work, nozzle shape of a jet fan is optimized numerically using three-dimensional Reynolds-averaged Navier-Stokes analysis. Standard $k-{epsilon}$ model is used as a turbulence closure. Response surface method is employed as an optimization technique. The objective function is defined as maximum throw distance. Three geometric variables, i.e., length and angle of nozzle, and interval between two nozzles, are selected as design variables. As the main result of the optimization, the throw distance has been improved effectively.