watch the video:
When i bake the displacement map, based on multiresolution, the output texture do not looks smooth. I tryed to increase the subdivision of the multires, but looks worst when i do it!
How can i get a smooth texture?
looks like you need to set the shading of the object to smooth. Press T for the tool shelf and click set smooth.
You’ll need to increase the number of polygons your object has by adding more subdivisions
thank you Richard and m9105826 for your replyes, i did both, if i add more subdivision the texture get worst… and i setted the shading of the object to smooth… maybe is a bug?
Added more faces in edit mode too:
do not work 
did a test, got the same bad results. You could do a bug report and show your first video.
but i could do it for you & direct them to this page if you wish
I found the solution, i just have to bake the multires, with a multires preview = 0 (zero) then it bakes very well!
interesting. Sounds like a workaround, not a proper solution. If this is indeed normal behavior, it has to be communicated in some way.
But glad it works for you now