Joint structure

Provided is a bonded structure in which a component member, which is provided with a ceramic part and a component electrode including a pair of internal electrodes and a pair of external electrodes, is electrically bonded to a circuit board, said bonded structure exhibiting stable electrical characteristics even in a high-humidity environment. The bonded structure includes: a component member in which a ceramic portion covered with a first protective layer, and a component electrode including a pair of internal electrodes exposed from the first protective layer, and a pair of external electrodes exposed from the first protective layer are formed on a first substrate, the internal electrodes being located in the ceramic portion, the external electrodes being located in the first protective layer, and the external electrodes being located in the first protective layer; the ceramic part has a thickness of 40 [mu] m or less; a circuit board having a pair of pad electrodes formed on a second base material; and a b