A liquid level detection device unit includes a liquid level detection device configured to detect a liquid level of liquid stored in a tank, and a fixing member fixing the liquid level detection device to inside of the tank. The liquid level detection device includes a device body, at least one terminal electrically connected to a detection unit in a housing of the device body, and a detection wire in which one end is electrically connected to an exposed part of the terminal exposed from the housing. At least one through opening is provided on an attachment surface of the fixing member so as to face the exposed part of the terminal and prevent the liquid from staying in a connection portion between the terminal and the detection wire.