  Knowledge of water in the solar system is important for understanding of a
wide range of evolutionary processes and the thermal history of the solar
system. To explore the existence of water in the solar system, it is
indispensable to investigate hydrated minerals and/or water ice on asteroids.
These water-related materials show absorption features in the 3-$\micron$ band
(wavelengths from 2.7 to 3.1 $\micron$). We conducted a spectroscopic survey of
asteroids in the 3-$\micron$ band using the Infrared Camera (IRC) on board the
Japanese infrared satellite AKARI. In the warm mission period of AKARI, 147
pointed observations were performed for 66 asteroids in the grism mode for
wavelengths from 2.5 to 5 $\micron$. According to these observations, most
C-complex asteroids have clear absorption features ($> 10\%$ with respect to
the continuum) related to hydrated minerals at a peak wavelength of
approximately 2.75 $\micron$, while S-complex asteroids have no significant
feature in this wavelength range. The present data are released to the public
as the Asteroid Catalog using AKARI Spectroscopic Observations (AcuA-spec).
