A bonding joining structure in which a heat generating body and a support comprising a metal are joined to each other via a joint portion composed of a sintered body of copper powder whose copper particles are composed of copper alone, wherein the bonding joining structure is a die bonding joining structure in which a die of a semiconductor device serves as the heat generating body, the outermost surface of support is composed of gold alone, an interdiffusion portion in which gold contained in the support and copper contained in the sintered body are diffused to each other is formed so as to straddle a bonding interface between the support and the sintered body, the interdiffusion portion contains a Cu 3 Au portion and a solid solution portion composed of a solid solution of gold and copper, the distribution of copper when viewed along the vertical cross-sectional direction of the bonding joining structure gradually decreases from the sintered body side toward the support side, the distribution of gold when viewed along the vertical cross-sectional direction of the bonding joining structure gradually increases from the sintered body side toward the support side, wherein the element distribution in a depth direction in the vicinity of the bonding interface between the sintered body and the support of the obtained bonding structure was determined using a scanning transmission electron microscope and the solid solution portion is located between the Cu 3 Au portion and the sintered body; and wherein a gold layer composed of gold alone is formed on a bottom surface of the die, the interdiffusion portion in which gold contained in the bottom surface of the die and copper contained in the sintered body are diffused to each other is formed so as to straddle a bonding interface between the die and the sintered body, and the interdiffusion portion contains Cu 3 Au and a solid solution of gold and copper. wherein the bonding joining structure is a die bonding joining structure in which a die of a semiconductor device serves as the heat generating body, the outermost surface of support is composed of gold alone, an interdiffusion portion in which gold contained in the support and copper contained in the sintered body are diffused to each other is formed so as to straddle a bonding interface between the support and the sintered body, the interdiffusion portion contains a Cu 3 Au portion and a solid solution portion composed of a solid solution of gold and copper, the distribution of copper when viewed along the vertical cross-sectional direction of the bonding joining structure gradually decreases from the sintered body side toward the support side, the distribution of gold when viewed along the vertical cross-sectional direction of the bonding joining structure gradually increases from the sintered body side toward the support side, wherein the element distribution in a depth direction in the vicinity of the bonding interface between the sintered body and the support of the obtained bonding structure was determined using a scanning transmission electron microscope and the solid solution portion is located between the Cu 3 Au portion and the sintered body; and wherein a gold layer composed of gold alone is formed on a bottom surface of the die, the interdiffusion portion in which gold contained in the bottom surface of the die and copper contained in the sintered body are diffused to each other is formed so as to straddle a bonding interface between the die and the sintered body, and the interdiffusion portion contains Cu 3 Au and a solid solution of gold and copper.