The ryō (両) is the currency used in the Naruto world. It is based on an old Japanese gold coin that was used in Japan before the Meiji period. It was later replaced by the yen. The exchange rate of a ryō is 10 yen.
Although money isn't focused on much in the story, certain prices and sums of money have been mentioned. For example, Asuma Sarutobi had a bounty of 35,000,000 ryō, five million ryō more than his fellow former Guardian Ninja, Chiriku. Shinobi usually earn their money from completing missions. The rewards for these range from 5,000 ryō for a D-rank mission to more than 1,000,000 ryō for an S-rank mission. In the anime, Utakata had been given a bounty of 5,000,000 ryō for his defection from Kirigakure.
In Naruto the Movie: Guardians of the Crescent Moon Kingdom, when Michiru Tsuki wrote a cheque to buy a circus, it had a dollar sign, suggesting that the Land of the Moon does not use ryō. Michiru spent $1,000,000,000 just to buy the circus, showing that the kingdom is very wealthy, and that he has little sense of spending moderately.
In episode 174 of the original Naruto anime, Kunihisa used something he called "Money Release Technique" (金遁の術, Kinton no Jutsu, English TV: Money Style Jutsu), which was used to simply buy whatever he wanted.