A flow meter includes: a flat substrate; a housing that houses the substrate and has an open in at least one surface; a cover that covers the substrate and covers an open surface of the housing; a support that supports the substrate and is in contact with the cover and the substrate; and a fixing unit that connects the substrate and the housing, in which, in a first region and a second region formed by dividing the substrate into two parts at a center in a longitudinal direction, the support is disposed in the first region, and the fixing unit is disposed in the second region.