Line-of-sight velocity and metallicity measurements of the Palomar 5 tidal streamCold stellar streams in the Milky Way (MW) halo are important tracersof the gravitational potential of our Galaxy in its outskirt, which iscurrently not well constrained. One of the best-known streams is Palomar 5 (Pal 5), a low-mass globular clusterin the outer MW halo, which exhibits a prominent long and thin tidalstream. We carried out medium-resolution multi-object spectroscopy usingSubaru/FOCAS and Keck/DEIMOS toward the Pal 5 cluster and itstidal stream. Our data cover an angular extent greater than 15 degrees,which is crucial to constrain the underlying gravitational potential viaa line-of-sight velocity gradient along the stream. Using line-of-sight velocity and metallicity of individual stars based on our data,we estimated possible range of the line-of-sight velocity towardeach projected location of the stream taking into account contaminationof field MW stars. We found that the estimated velocity rangesare consistent with those suggested in previous studies,while they are highly dependent on adopted prior assumptions aboutthe stream's velocity and its dispersion. The resulting uncertainties in the MW's gravitational potential would be significantly reduced with a deeper spectroscopic survey of the stream, which can beachieved by e.g. Subaru/PFS.