The purpose of this study is to control the jet diffusion by using the deforming nozzle. The shape of polypropylene nozzle can change from square shape into the cruciform shape smoothly. The velocity measurement of the jet flow was performed using X-type hot wire sensors and the constant temperature anemometer. The basic characteristics of the jet flow, such as the velocity distribution, the half value width and the turbulent intensities were obtained. Moreover, to catch the flow feature of the jet near the nozzle the flow visualization was conducted by using the Laser Light Sheet and the high speed video camera. As a result, it has been found that the diffusion of the jet issuing from the deforming nozzle is promoted, comparing with the case of the square nozzle jet.