  In this article, we study the magnetic moment of the pentaquark state $
\Theta^+(1540)$ as diquark-diquark-antiquark ($[ud][ud]\bar{s}$) state in the
framework of the light-cone QCD sum rules approach. The numerical results
indicate the magnetic moment of the pentaquark state $ \Theta^+(1540)$ is about
$\mu_{\Theta^+}=-(0.49\pm 0.06)\mu_N$.
