  In this paper, we consider the problem of estimating the drift parameter of
solution to the stochastic differential equation driven by a fractional
Brownian motion with Hurst parameter less than $1/2$ under complete
observation. We derive a formula for the likelihood ratio and prove local
asymptotic normality when $H \in (1/4,1/2)$. Our result shows that the
convergence rate is $T^{-1/2}$ for the parameters satisfying a certain equation
and $T^{-(1-H)}$ for the others.
