A lower electrode (4) can have an uneven surface structure. An upper electrode (6) can also have the uneven surface structure. A projecting portion of the upper electrode (6) projecting to the lower electrode side is positioned in a gap between projecting portions of the lower electrode (4) and the lower electrode (4) includes Cu as a main component. Young's moduli of a substrate (1), a stress adjustment layer (2), and the lower electrode (4) have a specific relation. Also, corner portions of radii (R1) of curvature positioned inside a projecting portion (4b) have a specific relation.