A clutch device has two clutch mechanisms each having a clutch drum in its inside. A driven plate and a cylinder are inside the clutch drum of each clutch mechanism, and ring-shaped primary and secondary springs are placed between the driven plate and the cylinder. A flat portion is provided at the inner peripheral edge on the projection surface side of the primary spring (1), and the flat portion can be in contact with a mating member at the beginning when a load is applied to the spring. A load produced by elastic deformation when the spring is made flat is adjusted to a desired value by the flat section. Blanks (1A, 2A) of the primary and the secondary springs are obtained by press forming of plate materials having the same thickness. In the press forming, a flat section (12A) is formed at an inner peripheral edge of the blank (1A) with consideration of its shape after it is bent.