Joined body

A joined body comprising:

• a first joined member;
• a second joined member;
• and
• a first joining layer that joins the first joined member and the second joined member,
• wherein the first joined member is a metal member and the second joined member is one selected from the group consisting of a metal member, a polyamide resin member, and a polyolefin resin member,
• the first joining layer is a layer formed of a resin composition containing a polyamide resin, a polyolefin resin, a modified elastomer having a reactive group capable of reacting with the polyamide resin, and a reaction product of the polyamide resin and the modified elastomer,
• the resin composition has a co-continuous phase including a continuous phase A formed of the polyamide resin and a continuous phase B formed of the polyolefin resin and has a dispersed domain a distributed in the continuous phase A, a finely dispersed subdomain a′ distributed in the dispersed domain a, a dispersed domain b distributed in the continuous phase B, and a finely dispersed subdomain b′ distributed in the dispersed domain b,
• the dispersed domain a is a dispersed domain formed of at least one selected from the group consisting of the polyolefin resin, and the reaction product of the polyamide resin and the modified elastomer,
• the dispersed domain b is a dispersed domain formed of at least one selected from the group consisting of the polyamide resin, and the reaction product of the polyamide resin and the modified elastomer,
• when the dispersed domain a is formed of the polyolefin resin, the finely dispersed subdomain a′ is a finely dispersed subdomain formed of at least one selected from the group consisting of the polyamide resin, the modified elastomer, and the reaction product of the polyamide resin and the modified elastomer,
• when the dispersed domain a is formed of the reaction product of the polyamide resin and the modified elastomer, the finely dispersed subdomain a′ is a finely dispersed subdomain formed of at least one selected from the group consisting of the polyamide resin, the polyolefin resin, and the modified elastomer,
• when the dispersed domain b is formed of the polyamide resin, the finely dispersed subdomain b′ is a finely dispersed subdomain formed of at least one selected from the group consisting of the polyolefin resin, the modified elastomer, and the reaction product of the polyamide resin and the modified elastomer,
• when the dispersed domain b is formed of the reaction product of the polyamide resin and the modified elastomer, the finely dispersed subdomain b′ is a finely dispersed subdomain formed of at least one selected from the group consisting of the polyamide resin, the polyolefin resin, and the modified elastomer, and
• an average thickness of the first joining layer is in a range of 300 to 700 μm.