Exhaust structure of engine

An exhaust structure of an engine, the exhaust structure comprising:

• an engine body in which a plurality of cylinders and a plurality of exhaust ports are formed, the plurality of cylinders being arranged in a cylinder arrangement direction, which is predetermined, the plurality of exhaust ports extending from the plurality of cylinders;
• and an exhaust passage through which exhaust gas led out from the engine body flows, wherein
• when one side in an engine width direction, which is orthogonal to the cylinder arrangement direction and an up-down direction, is taken as an exhaust side, and an opposite side of the exhaust side is taken as an intake side, a plurality of exhaust port opening ends are open on a side surface of the engine body on the exhaust side in a state of being arranged along the cylinder arrangement direction, the plurality of exhaust port opening ends being outlets of the plurality of exhaust ports,
• the exhaust passage includes an upstream-side passage and a catalyst device having a cylindrical shape, the upstream-side passage extending from the plurality of exhaust port opening ends, the catalyst device being provided at a position lower than the plurality of exhaust port opening ends, and purifying exhaust gas that passes through the upstream-side passage,
• the upstream-side passage includes a plurality of independent passages arranged side by side in the cylinder arrangement direction, and individually connected to the plurality of exhaust port opening ends, the upstream-side passage having a shape that is bent in such a way as to bulge toward the exhaust side from the plurality of exhaust port opening ends and to extend downward, and
• the catalyst device is disposed at a position between the side surface of the engine body on the exhaust side and the upstream-side passage in an attitude in which a center axis of the catalyst device extends along the cylinder arrangement direction, the position overlapping with the plurality of independent passages when viewed along the up-down direction, and overlapping with the upstream-side passage when viewed along the engine width direction.