The cavity portion 103 is formed between the substrate 301, the lower electrode 102 formed on the substrate 301, the lower insulating film 303 formed on the lower electrode 102, and the lower insulating film 303. And the upper electrode 105 formed on the upper insulating film 305. The cavity 103 overlaps the lower electrode 102. The upper electrode 105 includes the cavity 103 and the lower electrode 102. And the upper insulating film 305 is an insulating film having a leakage current larger than that of the lower insulating film 303.基板３０１と、基板３０１上に形成された下部電極１０２と、下部電極１０２上に形成された下層絶縁膜３０３と、下層絶縁膜３０３上に形成され、下層絶縁膜３０３との間に空洞部１０３を形成する上層絶縁膜３０５と、上層絶縁膜３０５上に形成された上部電極１０５と、を有し、空洞部１０３は、下部電極１０２と重なり、上部電極１０５は、空洞部１０３および下部電極１０２と重なり、上層絶縁膜３０５は、下層絶縁膜３０３よりもリーク電流の大きい絶縁膜とした超音波探触子。
