Exhaust Manifold for internal combustion engine

An exhaust manifold provides improved output by suppressing exhaust interference between cylinders at the exhaust manifold. The exhaust manifold of an internal combustion engine, comprises a collector case (23) having an upstream end and a downstream end; and a plurality of exhaust tubes (21a-21d) having inlet ends adapted to be connected to exhaust ports of the internal combustion engine and outlet ends connected to said upstream end of said collector case (23) by merging portions, wherein said outlet ends include linear portions (24) are disposed contiguously with said merging portions, where said exhaust tubes (21a-21d) merge with said collector case (23), and wherein said linear portions (24) are arranged in pairs of parallel linear portions, one pair of parallel linear portions (24) being slanted with respect to a second pair of parallel linear portions (24), and comprise center axes (C2,C2) intersecting at an intersection point (G) inside said collector case (23) or downstream thereof, and said exhaust tubes (21a,21b and 21c,21d) with said inlet ends arranged to receive exhaust gas from cylinders, whose firing orders are not successive, constitute one pair of parallel linear portions (24).