  We investigate the production of the pentaquark $\Theta^+$ baryon via the
$\gamma n\to K^-\Theta^+$ and $\gamma p\to \bar{K}^0 \Theta^+$ processes,
focusing on the parity of the $\Theta^+$. Using the effective Lagrangians, we
calculate the total and differential cross sections with the spin of the
$\Theta^+$ presumed to be 1/2. We employ the coupling constant of the
$KN\Theta$ vertex determined by assuming its mass and the decay width to be
$1540 {\rm MeV}$ and $15 {\rm MeV}$. That of the $K^*N\Theta$ is taken to be
about a half of the $KN\Theta$ coupling constant. We estimate the cutoff
parameter by reproducing the total cross section of the $\gamma p \to K^+
\Lambda$ reaction. It turns out that the total cross section for the $\gamma
n\to K^- \Theta^+$ process is about four times larger than that of the $\gamma
p\to\bar{K}^0\Theta^+$. We also find that the cross sections for the production
of the positive-parity $\Theta$ are about ten times as large as those for the
negative-parity ones.
