An assembly of a cylinder head, fuel injection valves and an intake manifold configured to be mounted on an internal combustion engine in which the fuel injection valves are installed so as to be located near one side face of the cylinder head on a top face of the cylinder head, the intake manifold being connected to the one side face of the cylinder head so as to face the fuel injection valves, the intake manifold comprising: a plurality of intake branch pipes (9A, 9B, 9C, 9D) that are made of resin, the plurality of intake branch pipes (9A, 9B, 9C, 9D) being suitable to introduce intake air into corresponding intake ports of the cylinder head, each of the intake branch pipes including a first split branch pipe and a second split branch pipe, the second split branch pipe being connected to the first split branch pipe; wherein each first split branch pipe includes a flange portion at a distal end of the first split branch pipe, each flange portion has a contact face at one side face of the flange portion, each contact face contacts the cylinder head, each flange portion includes a first joint face at the other side face of the flange portion, each flange portion is connected to the cylinder head, each second split branch pipe includes a joint portion at a distal end of the second split branch pipe, each joint portion has a second joint face that is connected to a corresponding one of the first joint faces, the flange portions and the joint portions are connected to the cylinder head such that any line defined by the intersection of the plane including the first and second joint faces (32b, 33a) with a plane perpendicular to the top face of the cylinder head and perpendicular to the first joint faces and the second joint faces is oriented toward positions clear of the fuel injection valves, the assembly being characterized in that each joint portion is formed such that a length of the second joint face in the direction of the line is longer than a maximum spaced distance along the direction of the line between the corresponding fuel injection valve and the corresponding flange portion. a plurality of intake branch pipes (9A, 9B, 9C, 9D) that are made of resin, the plurality of intake branch pipes (9A, 9B, 9C, 9D) being suitable to introduce intake air into corresponding intake ports of the cylinder head, each of the intake branch pipes including a first split branch pipe and a second split branch pipe, the second split branch pipe being connected to the first split branch pipe; wherein each first split branch pipe includes a flange portion at a distal end of the first split branch pipe, each flange portion has a contact face at one side face of the flange portion, each contact face contacts the cylinder head, each flange portion includes a first joint face at the other side face of the flange portion, each flange portion is connected to the cylinder head, each second split branch pipe includes a joint portion at a distal end of the second split branch pipe, each joint portion has a second joint face that is connected to a corresponding one of the first joint faces, the flange portions and the joint portions are connected to the cylinder head such that any line defined by the intersection of the plane including the first and second joint faces (32b, 33a) with a plane perpendicular to the top face of the cylinder head and perpendicular to the first joint faces and the second joint faces is oriented toward positions clear of the fuel injection valves, the assembly being characterized in that each joint portion is formed such that a length of the second joint face in the direction of the line is longer than a maximum spaced distance along the direction of the line between the corresponding fuel injection valve and the corresponding flange portion.