An internal combustion engine comprising: a cylinder block including a plurality of cylinders; a cylinder head including an in-head manifold and an in-head coolant passage, the in-head manifold connecting to each of combustion chambers of the cylinders, the in-head manifold configured to collect exhaust gases from the combustion chambers, and the in-head manifold connecting to an exhaust outlet of the cylinder head, a central axis of the exhaust outlet being located, in a cylinder array direction of the cylinders, closer to one cylinder out of the two outermost cylinders than a center of a straight line connecting central axes of the two outermost cylinders to each other, and the cylinder array direction being a direction of extension of a straight line that passes through central axes of the cylinders on a plane orthogonal to the central axes of the cylinders; and a turbocharger including an inlet port, the inlet port connecting to the exhaust outlet of the cylinder head, the inlet port including a first wall portion and a second wall portion, the first wall portion being located between the one cylinder and a central axis of the inlet port in the cylinder array direction, the second wall portion being located on an opposite side of the central axis of the inlet port from the first wall portion, characterized in that the first wall portion includes a thick-walled portion and a thin-walled portion, the thick-walled portion being greater in pipe wall thickness than the second wall portion, the thin-walled portion being smaller in pipe wall thickness than the thick-walled portion, and the thin-walled portion being located upstream of the thick-walled portion in a direction of exhaust gas flow. a cylinder block including a plurality of cylinders; a cylinder head including an in-head manifold and an in-head coolant passage, the in-head manifold connecting to each of combustion chambers of the cylinders, the in-head manifold configured to collect exhaust gases from the combustion chambers, and the in-head manifold connecting to an exhaust outlet of the cylinder head, a central axis of the exhaust outlet being located, in a cylinder array direction of the cylinders, closer to one cylinder out of the two outermost cylinders than a center of a straight line connecting central axes of the two outermost cylinders to each other, and the cylinder array direction being a direction of extension of a straight line that passes through central axes of the cylinders on a plane orthogonal to the central axes of the cylinders; and a turbocharger including an inlet port, the inlet port connecting to the exhaust outlet of the cylinder head, the inlet port including a first wall portion and a second wall portion, the first wall portion being located between the one cylinder and a central axis of the inlet port in the cylinder array direction, the second wall portion being located on an opposite side of the central axis of the inlet port from the first wall portion, characterized in that the first wall portion includes a thick-walled portion and a thin-walled portion, the thick-walled portion being greater in pipe wall thickness than the second wall portion, the thin-walled portion being smaller in pipe wall thickness than the thick-walled portion, and the thin-walled portion being located upstream of the thick-walled portion in a direction of exhaust gas flow.