A ceramic joined body (1) includes: a pair of ceramic plates (2,3) that include a conductive material; and a conductive layer (4) and an insulating layer (5) that are interposed between the pair of ceramic plates (2, 3), a porosity at an interface between the pair of ceramic plates (2, 3) and the insulating layer (5) is 4% or less, and a ratio of an average primary particle diameter of an insulating material which forms the insulating layer (5) to an average primary particle diameter of an insulating material which forms the ceramic plates (2, 3) is more than 1.