A fluid analyzer includes a substrate, a quantum cascade laser formed on a surface of the substrate and including a first light-emitting surface and a second light-emitting surface facing each other, a first quantum cascade detector formed on the surface and including the same layer structure as the quantum cascade laser and a first light incident surface facing the first light-emitting surface, a second quantum cascade detector formed on the surface and including the same layer structure as the quantum cascade laser and a second light incident surface facing the second light-emitting surface, and a resin member covering at least the second light-emitting surface and the second light incident surface and having optical transparency and an electrical insulation property. A first space in which a fluid to be analyzed is disposed is provided in a first area between the first light-emitting surface and the first light incident surface.