To provide a management device of a game machine capable of adopting highly reliable data.

During a special prize game state (big winning), the signal characteristics of output signals from the game machine are measured, and whether or not a measured value (the input time of big winning signals, the number of prize balls based on prize ball signals) is smaller than a prescribed value (prescribed time, prescribed number) is decided. A special prize decision means (big winning judgement circuit 132) decides that a first special prize game state (normal big winning) is generated when the measured value is the prescribed value or larger and decides that a second special prize game state (sudden probability variable big winning) is generated when it is smaller than the prescribed value. On the basis of the decision result, a special prize number-of-times sum-up means (big winning number-of-times sum-up circuit 126) sums up the number of times of the generation of the first special prize game state and the number of times of the generation of the second special game state, and a summed-up value is displayed at a display means (calling lamp unit 10, information display terminal).