  We have carried out a deep imaging survey for H$\alpha$ emitting galaxies at
$z\approx$0.24 using a narrowband filter tuned with the redshifted line. The
total sky area covered is 706 arcmin$^2$ within a redshift range from 0.234 to
0.252 ($\delta z$=0.018). This corresponds to a volume of 3.9$\times10^3$
Mpc$^3$ when $\Omega_{\rm matter}=0.3$, $\Omega_\Lambda=0.7$, and
$H_{\mathrm{0}}$=70 km s$^{-1}$ Mpc$^{-1}$ are adopted. We obtain a sample of
348 H$\alpha$ emitting galaxies whose observed emission-line equivalent widths
are greater than 12 \AA. We find an extinction-corrected H$\alpha$ luminosity
density of $10^{39.65^{+0.08}_{-0.12}}$ ergs s$^{-1}$ Mpc$^{-3}$. Using the
Kennicutt relation between the H$\alpha$ luminosity and star formation rate,
the star formation rate density in the covered volume is estimated as
$0.036^{+0.006}_{-0.012}$ $M_{\sun}$ yr$^{-1}$ Mpc$^{-3}$. This value is higher
by a factor of 3 than the local SFR density.
