A controller includes a storage device that stores a load overflow reference value defined by a mutual relation between a load value of a work target object, a posture of a work implement, and a movement state of the work implement. The controller calculates the posture of the work implement, and calculates a physical quantity (for example, a swing speed) indicating the movement state of the work implement. The controller estimates whether or not the work implement has caused a load overflow during the transportation of the work target object on the basis of the reference value stored in the storage device, the calculated load value of the work target object, the calculated posture of the work implement, and the calculated physical quantity indicating the movement state of the work implement. When the controller determines that the load overflow has occurred, the controller makes a notification to that effect on a monitor.