A work machine comprising: a machine body (11, 12); a boom having a boom proximal end portion which is a proximal end portion supported by the machine body so as to be raised and lowered; an arm having an arm proximal end portion rotatably supported by a distal end portion of the boom and an arm distal end portion which is a distal end portion on an opposite side of the arm proximal end portion; a distal end attachment having a distal end attachment proximal end portion which is a proximal end portion rotatably supported by the arm distal end portion; a boom cylinder which is a hydraulic cylinder that operates so as to raise and lower the boom with respect to the machine body; an arm cylinder which is a hydraulic cylinder that operates so as to rotate the arm with respect to the boom; a distal end cylinder which is a hydraulic cylinder that operates so as to rotate the distal end attachment with respect to the arm; an attitude detector (61, 62, 63) that detects attitudes of the boom, the arm, and the distal end attachment; a holding pressure detector (64, 65) that detects a holding pressure of the boom cylinder; and a controller including a property calculation section, characterised in that the property calculation section includes: calculating a horizontal distance between the boom proximal end portion and the arm distal end portion based on a detection signal input from the attitude detector; calculating a weight of the distal end attachment based on the horizontal distance and a detection signal input from the holding pressure detector in a state where the distal end attachment is disposed at a pressure release position which is a position when a pressure of the distal end cylinder is released; and calculating a gravity center position of the distal end attachment based on the weight of the distal end attachment, a detection signal input from the holding pressure detector, and a detection signal input from the attitude detector in a state where the distal end attachment is disposed at a displacement position which is a position different from the pressure release position. a machine body (11, 12); a boom having a boom proximal end portion which is a proximal end portion supported by the machine body so as to be raised and lowered; an arm having an arm proximal end portion rotatably supported by a distal end portion of the boom and an arm distal end portion which is a distal end portion on an opposite side of the arm proximal end portion; a distal end attachment having a distal end attachment proximal end portion which is a proximal end portion rotatably supported by the arm distal end portion; a boom cylinder which is a hydraulic cylinder that operates so as to raise and lower the boom with respect to the machine body; an arm cylinder which is a hydraulic cylinder that operates so as to rotate the arm with respect to the boom; a distal end cylinder which is a hydraulic cylinder that operates so as to rotate the distal end attachment with respect to the arm; an attitude detector (61, 62, 63) that detects attitudes of the boom, the arm, and the distal end attachment; a holding pressure detector (64, 65) that detects a holding pressure of the boom cylinder; and a controller including a property calculation section, characterised in that the property calculation section includes: calculating a horizontal distance between the boom proximal end portion and the arm distal end portion based on a detection signal input from the attitude detector; calculating a weight of the distal end attachment based on the horizontal distance and a detection signal input from the holding pressure detector in a state where the distal end attachment is disposed at a pressure release position which is a position when a pressure of the distal end cylinder is released; and calculating a gravity center position of the distal end attachment based on the weight of the distal end attachment, a detection signal input from the holding pressure detector, and a detection signal input from the attitude detector in a state where the distal end attachment is disposed at a displacement position which is a position different from the pressure release position. calculating a horizontal distance between the boom proximal end portion and the arm distal end portion based on a detection signal input from the attitude detector; calculating a weight of the distal end attachment based on the horizontal distance and a detection signal input from the holding pressure detector in a state where the distal end attachment is disposed at a pressure release position which is a position when a pressure of the distal end cylinder is released; and calculating a gravity center position of the distal end attachment based on the weight of the distal end attachment, a detection signal input from the holding pressure detector, and a detection signal input from the attitude detector in a state where the distal end attachment is disposed at a displacement position which is a position different from the pressure release position.