To provide a prize-winning ball lottery device of a game machine which prevents a rise in the jackpot winning probability to an improper extent even in a structure of facilitating the winning of the jackpot winning slot for a lottery mechanism (distribution mechanism) of the game machine.

The prize-winning ball lottery device of the game machine includes a guide part which guides game balls shot out onto the surface of a game board of the game machine to make them ready for winning a prize, a lottery part for the game balls to be supplied and a storage part for storing the game balls made ready for winning a prize by the guide part. The storage part supplies the game balls to the lottery part except for those positioned at the head of those stored. The storage part has a storage groove part which stores a plurality of game balls by alignment, a discharge port provided at the tipmost position of the storage groove part, an inclined surface toward the lottery part and a magnet piece free to get into or out of the storage groove via the upper part of the discharge port.