  Gambling is one of the basic economic activities that humans indulge in. An
investigation of gambling activities provides deep insights into the economic
actions of people and sheds lights on the study of econophysics. In this paper
we present an analysis of the distribution of the final odds of the races
organized by the Japan Racing Association. The distribution of the final odds
$P_o(x)$ indicates a clear power law $P_o(x)\propto 1/x$, where $x$ represents
the final odds. This power law can be explained on the basis of the assumption
that that every bettor bets his money on the horse that appears to be the
strongest in a race.
