  An inner main-belt asteroid, P/2010 A2, was discovered on January 6th, 2010.
Based on its orbital elements, it is considered that the asteroid belongs to
the Flora collisional family, where S-type asteroids are common, whilst showing
a comet-like dust tail. Although analysis of images taken by the Hubble Space
Telescope and Rosetta spacecraft suggested that the dust tail resulted from a
recent head-on collision between asteroids (Jewitt et al. 2010; Snodgrass et
al. 2010), an alternative idea of ice sublimation was suggested based on the
morphological fitting of ground-based images (Moreno et al. 2010). Here, we
report a multiband observation of P/2010 A2 made on January 2010 with a 105 cm
telescope at the Ishigakijima Astronomical Observatory. Three broadband
filters, $g'$, $R_c$, and $I_c$, were employed for the observation. The unique
multiband data reveals that the reflectance spectrum of the P/2010 A2 dust tail
resembles that of an Sq-type asteroid or that of ordinary chondrites rather
than that of an S-type asteroid. Due to the large error of the measurement, the
reflectance spectrum also resembles the spectra of C-type asteroids, even
though C-type asteroids are uncommon in the Flora family. The reflectances
relative to the $g'$-band (470 nm) are 1.096$\pm$0.046 at the $R_c$-band (650
nm) and 1.131$\pm$0.061 at the $I_c$-band (800 nm). We hypothesize that the
parent body of P/2010 A2 was originally S-type but was then shattered upon
collision into scaterring fresh chondritic particles from the interior, thus
forming the dust tail.
