Abstract: In an insert molded product 10 according to the present invention, a primary molded part 2 formed around an insert member 1 in primary molding has an external surface of convexo-concave shape in which convex portions 2a, 2a′ and concave portions 2b, 2b′, alternately arranged in the longitudinal direction of the insert member, and a secondary molded part 3 formed around the primary molded part in a secondary molding has an external surface which is generally flat in parallel to the longitudinal direction of the insert member. Therefore, in the secondary molded part also, convex portions 3a, 3a′ and concave portions 3b, 3b′ are alternately arranged. A protrusion 7 for welding is provided on the convex portion of primary molded part in the rear of the convex portion 2a that is provided on the primary portion for regulation of flow at the time of secondary welding.