A folding test machine to measure the durability against folding can be operated by minor adjustment even if a radius of curvature of the folding or an arc length of the folding is changed. A fixed wall and a moveable wall are opposingly provided in an approximately box-shaped frame and a holding part to hold a workpiece is provided on the top of each of the fixed wall and the moveable wall in a rotatable manner in a vertical plane of the rotation. And the workpiece and a plate spring are held on the respective opposing end portions so as to be bridged between the fixed wall and the moveable wall in a curved manner such that the moveable wall is moved closer to and farther from the fixed wall repeatedly such that the work is folded repeatedly.