A humidity sensor includes: a sensor chip including a capacitive humidity sensor element and a connection electrode, wherein the capacitive humidity sensor element includes a humidity sensitive film having relative permittivity changeable in accordance with humidity, and wherein the connection electrode is electrically connected to the humidity sensor element; a lead plate electrically connected to the connection electrode; and a mold for covering a connection portion between the connection electrode and the lead plate. The mold is disposed on the sensor chip and includes a groove. The humidity sensitive film is disposed in the groove. The humidity sensitive film has a height in the groove, the height equal to or lower than a surface of the mold. The height of the humidity sensitive film in the groove is homogeneous.