A liquid detection device includes a casing main body in which a passage is formed and exposed in an opening, a sensor base that is disposed to face the passage of the casing main body, a sensor chip provided on the sensor base, a film that seals the opening in which the sensor base is held, and a partition wall that divides the passage into an upstream side and an downstream side. The sensor chip has a sensor cavity, and the sensor base has a first hole that guides a liquid from the upstream side to the sensor cavity, and a second hole that guides the liquid from the sensor cavity to the downstream side. The sensor base can come into contact with the casing main body through only the partition wall in a depth direction of the opening.