Abstract: There is disclosed a solid semiconductor element which very efficiently detects information about a liquid and bidirectionally exchanges the information with the outside. The solid semiconductor element is disposed in a liquid container, and includes at least energy converting unit, information acquiring unit, and information communicating unit. The energy converting unit converts an electromotive force from the outside to a power, and operates the information acquiring unit and information communicating unit. The information acquiring unit acquires the information about the liquid in which the solid semiconductor element is disposed from the liquid, and the information communicating unit transmits the information acquired by the information acquiring unit to the outside.