The present invention provides a joined body having a first member, a second member and a joining material interposed between the first and second members. The joining material has a porous bone structure with open pores and made of a sintered product of metal powder and impregnated phase impregnated into the open pores. The impregnated phase has polycrystalline substance made from a metal oxide and at least one of a nitride and an oxynitride. The joined body has improved resistance against fatigue and fracture, even when the body is subjected to repeated thermal cycles between high and room temperatures.