  Applying AdS/CFT correspondence, we study the effect of a constant magnetic
field $\mathcal{B}$ on the drag force associated with a heavy quark moving
through a strongly-coupled $\mathcal{N}=4$ supersymmetric Yang-Mills (SYM)
plasma. The quark is considered moving transverse and parallel to
$\mathcal{B}$, respectively. It is shown that for transverse case, the drag
force is linearly dependent on $\mathcal{B}$ in all regions. While for parallel
case, the drag force increases monotonously with increasing $\mathcal{B}$ and
also reveals a linear behavior in the regions of strong $\mathcal{B}$. In
addition, we find that $\mathcal{B}$ has important effect for transverse case
than parallel.
