An axial force measurement device includes a frame, a tightening actuation unit that performs tightening operation upon a screw type tube fitting installed upon a tube upon which is formed an annular portion projecting in the radially outward direction from the tube, a testing member, and a mating member holding unit that holds the testing member into which the tube fitting is screwed and that is coupled to the tube. The tightening actuation unit and the mating member holding unit are provided to the frame in line along the direction of a reference axis that extends in the direction of the center line of the tube fitting and the tube axis of the tube. The testing member has a first part that engages with the tube fitting, and a second part against which the annular portion of the tube is pressed.