  In this paper we prove that the fifth order equation arising from the KdV
hierarchy $ \partial_tu + \partial_x^5u + c_1\partial_x u\partial_x^2u +
c_2u\partial_x^3u = 0 $ is locally well-posed in $ H^s(\mathbb{R}) $ for $ s>
5/2. Also, we prove the solution map of the equation is not uniformly
continuous for $s>0$.
