To provide a connecting structure of a car body structural member in a vehicle or the like, capable of improving the strength while reducing a weight of the car body structural member forming a car body part.

In this connecting member for a main structure member 16 forming the car body part and sub-structural members 18 to be connected to the main structural part, the main structural member is provided with a box- shaped cross section, reinforcement pins 19 are respectively penetrated along the connecting direction of the sub-structural members near the connecting part with the sub-structural members, connecting members 20 respectively superposed to the main structural member, the sub-structural member, and the reinforcement pin are mounted at corner parts of the connecting parts of the main structure member and the sub-structural members, each connecting member is integrated with the main structural member, the sub-structural member and the reinforcement pin respectively by welding, and both ends of the reinforcement pin are integrated with the main structural member by welding.