Recent years, the technology of DNA origami is attracting keen interest for the synthesis of various nanostructures.　But there are only few example of DNA origami with a rotating part, which are found in nature or industries, such as flagellum movement of Eugelena, turbines, and motors. Further, the creation of the macroscopic-scale device only with DNA origami, which works with the macroscopic output or input signals such as a mechanical one, is difficult because the synthesis of DNA-origami in large amount costs a lot. Here, we fabricate the device which detects the flow of surrounding water by combining inorganic nanoporous substrate with nanoscale weathercock made of DNA origami. The DNA weathercock consist of a blade and shaft parts are attached with a fluorescence molecule. We mount the DNA weathercock into the nanopore of the inorganic nanoporous substrate of size-tunable anodizing alumina, so that the DNA weathercock can freely rotate. When we give a flow, the DNA weathercock turns to the direction of the flow. We observe the behavior of fluorescence molecule with a fluorescence microscope or even by our eye through a polarizers set on the device.