We introduce analysis of arbitrage opportunities in the foreign exchange market by using high-frequency data. We showed two kinds of arbitrage opportunities, negative spread arbitrages and triangle arbitrages, and we modeled the occurrence of the arbitrage with volatility, the number of deals and the number of computer traders. The market has changed over the last ten years. In particular an emergence of computer traders, which have trading algorithms in computers, is one of the biggest news in financial markets, and the computer traders can detect triangular arbitrages much faster than human traders. We also modeled the disappearance probability of triangular arbitrages within one second that is the minimum observation interval of our data by using volatility, the number of deals and the number of computer traders.