A high-aspect ratio structure production method and an ultrasonic probe production method of the present invention include: forming, in a principal surface of a substrate, a plurality of pores each extending in a direction intersecting the principal surface; plugging, among the plurality of pores, one or more pores formed in a first region; and forming a recess in a second region by a wet etching process. A high-aspect ratio structure includes a grating having a plurality of convex portions, wherein each of the plurality of convex portions is provided with a plugging member plugging a plurality of pores formed therein in a thickness direction of the structure.