  We consider a Cauchy problem of energy-critical fractional Schr\"odinger
equation with Hartree nonlinearity below the energy space. Using a method of
randomization of functions on $\mathbb{R}^d$ associated with the Wiener
decomposition, introduced by \'{A}. B\'{e}nyi, T. Oh, and O. Pocovnicu
\cite{beohpo1,beohpo2}, we prove that the Cauchy problem is almost surely
locally well-posed. Our result includes Hartree Schr\"odinger equation ($\alpha
= 2$).
