Next, as illustrated in FIG. 17B, when laminate films 201 and 202 are curved, deformation is performed with laminate film 202 on the lower side on the inner diameter side as a base. Since radius R2 of the top surface of: protrusion 209 is greater than radius R1 of laminate film 202 on the lower side, curved circumferential length L2 of the top surface of protrusion 209 is greater than uncurved length L1 (L2>L1).

In other words, laminate film 201 on the upper side needs to extend due to the curvature. However, since laminate films 201 and 202 are unlikely to extend, deformation is performed in a direction in which laminate film 202 on the lower side shrinks. Laminate film 202 on the lower side shrinks by the difference between the lengths L1 and L2 (L2-L1) and wrinkling or cracking appears on the surfaces of laminate films 201 and 202.

FIGS. 18A and 18B are diagrams illustrating the curved state in the related art in which a wave shape is formed on the surfaces of laminate films 201 and 202.