To provide a joined structure of dissimilar metallic materials where a part of an insert member is cast-in with a casting so as to join the insert member to the casting, by which the generation of electroerosion is prevented at the boundary part between the terminal face of the casting and the root of the insert member.

In the joined structure of dissimilar metallic materials, a first member 60 and a second member 70 are mutually composed of dissimilar metallic materials, and, when the first member is cast, a part 71 of the second member is cast in with the first member so as to join the second member to the first member. The second member has an extending part extending from the terminal face 67a in the first member to the outer part. The terminal face is formed so as to be tapered toward the extending part.