PURPOSE: To prevent coffee beans from jumping in a hopper, and to prevent harsh noise from being generated in the hopper, and to prevent the coffee beans from remaining without being ground, by a method wherein while the coffee beans are being ground, a grinder-driving motor is temporarily decelerated or stopped.

CONSTITUTION: When an electric current is applied to a motor 9 for the title mill, a grinder 11 is rotated and coffee beans on a bean-receiving part 16 are ground, and with the grind of the beans, the coffee beans in a hopper 14 are supplied to the side of the grinder 11 little by little through a bean-passing port 15 and are ground. Since a projection 17 on the grinder 11 projects inside a lower end opening 14c of the hopper 14 and the coffee beans are stirred, the beans are prevented from plugging. In this way, the coffee beans in the hopper 14 are settled and the coffee beans are smoothly supplied to the side of a mill case 1 through the lower end opening 14c. On the other hand, a control device 21 provided under the motor 9 controls the motor 9 and a heater 5, and while the mill is being driven, the motor 9 is temporarily stopped. In this way, the coffee beans in the hopper 14 are settled, and the coffee beans are smoothly supplied to the side of the mill case 1 through the lower end opening 14c.