A ceramic circuit board that includes a ceramic insulator layer, grounding pattern conductors, connection lands disposed on a first surface of the ceramic circuit board, and grounding electrodes disposed on a second surface of the ceramic circuit board and connected to the grounding pattern conductors. Each of the grounding pattern conductors contains a metal and an oxide and includes a pattern main portion disposed inside the ceramic circuit board and an extended portion in which a first end thereof is connected to the pattern main portion and a second end thereof is exposed at a side surface of the ceramic circuit board. The metal content of the extended portion is lower than the metal content of the pattern main portion.