a rotary crusher;

a hydraulic motor for rotating the rotary crusher, wherein the hydraulic motor is a capacity variable motor that can be switched between a predetermined capacity and a large capacity;

a feeder for feeding an object to be crushed to the rotary crusher;

a controller for controlling the feeder and the hydraulic motor;

a load detector for detecting a loading state of the hydraulic motor;

a load judging device for judging whether the loading state of the hydraulic motor detected by the load detector is in an overloaded state or an underloaded state;

a feeding amount controller for decreasing or stopping a feeding by the feeder of the object to be crushed when the load judging device judges that the hydraulic motor is in the overloaded state and for increasing or starting the feeding by the feeder of the object to be crushed when the load judging device judges that the hydraulic motor is in the underloaded state; and

a motor capacity controller for changing a capacity of the capacity-variable motor to the large capacity when the load judging device judges that the hydraulic motor is in the overloaded state;

wherein the feeding amount controller includes:

a crushing duration time measuring unit for measuring a crushing duration time between time points when the feeding of the object to be crushed is increased or started and when the feeding of the object to be crushed is decreased or stopped;

a time judging unit for judging whether the measured crushing duration time is longer than a predefined set time; and

a feeding amount adjusting unit that decreases a capability of the feeder in a subsequent feeding process when the measured crushing duration time is equal to or shorter than the set time, and increases the capability of the feeder in the subsequent feeding process when the measured crushing duration time is longer than the set time.