  We investigate the herd behavior of returns for the yen-dollar exchange rate
in the Japanese financial market. It is obtained that the probability
distribution $P(R)$ of returns $R$ satisfies the power-law behavior $P(R)
\simeq R^{-\beta}$ with the exponents $ \beta=3.11$(the time interval $\tau=$
one minute) and 3.36($\tau=$ one day). The informational cascade regime appears
in the herding parameter $H\ge 2.33$ at $\tau=$ one minute, while it occurs no
herding at $\tau=$ one day. Especially, we find that the distribution of
normalized returns shows a crossover to a Gaussian distribution at one time
step $\Delta t=1$ day.
