To provide a ball lift mechanism in an island of pachinko game machines which prevents the lowering of endurance by enabling continuous supply of pachinko balls to a ball hoisting device.

An auxiliary storage tank 3 is installed between a ball grinder 1 and a sprocket type ball hoisting device 2. An upper limit detection means 33 and a lower limit detection means 34 for the holding quantity of balls are arranged in the auxiliary storage tank 3. A control means 40 starts the ball hoisting device 2 by an output signal of the upper limit detection means 33 or stops the operation of the ball hoisting device 2 by an output signal of the lower limit detection means 34. As the holding quantity of balls in the auxiliary storage tank 3 decreases, the ball hoisting device 2 is stopped thereby enabling prevention of troubles as caused by failure in the continuous supply of pachinko balls.