This paper reports a measurement technique for surface waves on a liquid lithium jet, and its experimental results for the purpose of study on a Li target of the International Fusion Materials Irradiation Facility (IFMIF). The statically characteristic of the waves was successfully clarified by a contact-type liquid level detector and an analysis method of the obtained data newly proposed in this paper. The detail procedure of the measurement method is described in this paper. As the results, it was found that the wave distributions in the all jet velocity range up to 15m/s were conformed each other in normalized form and Rayleigh distribution which is one of popular model to show irregular water waves, and found that the mean wave height increased with increasing of the flow velocity.