A saddle riding vehicle, comprising: a unit swing engine that includes a crankcase and a cylinder portion having a cylinder axis extending from the crankcase in a vehicle fore-aft direction and that is swingably supported on a vehicle body frame ; an exhaust pipe connected with the cylinder portion ; a catalyst unit disposed in the exhaust pipe ; an exhaust gas sensor disposed in the exhaust pipe , and a muffler that is a downstream end portion of the exhaust pipe , wherein the unit swing engine is supported on the vehicle body frame via a vehicle body-side rocking shaft disposed superior to the unit swing engine , in a side view, at least a part of the catalyst unit is disposed inferior to the cylinder portion and is disposed in a region between a first imaginary line (L1) and a second imaginary line (L2), the first imaginary line (L1) connecting the vehicle body-side rocking shaft and a front end of the crankcase , the second imaginary line (L2) connecting an exhaust pipe connection portion of the cylinder portion , with which an end of the exhaust pipe is connected, and the vehicle body-side rocking shaft , the exhaust pipe includes an upstream side exhaust pipe located upstream of the catalyst unit , characterized in that the upstream side exhaust pipe includes a downward extension portion that extends from the exhaust pipe connection portion downwardly, a lateral extension portion that extends from a lower end of the downward extension portion toward a side opposite from the muffler in the vehicle width direction, and a curved portion that is bent from an outer end of the lateral extension portion toward a side of the muffler and connected to the catalyst unit disposed posterior to the downward extension portion , and the exhaust gas sensor is disposed in the upstream side exhaust pipe at a position inferior to the cylinder portion . a unit swing engine that includes a crankcase and a cylinder portion having a cylinder axis extending from the crankcase in a vehicle fore-aft direction and that is swingably supported on a vehicle body frame ; an exhaust pipe connected with the cylinder portion ; a catalyst unit disposed in the exhaust pipe ; an exhaust gas sensor disposed in the exhaust pipe , and a muffler that is a downstream end portion of the exhaust pipe , wherein the unit swing engine is supported on the vehicle body frame via a vehicle body-side rocking shaft disposed superior to the unit swing engine , in a side view, at least a part of the catalyst unit is disposed inferior to the cylinder portion and is disposed in a region between a first imaginary line (L1) and a second imaginary line (L2), the first imaginary line (L1) connecting the vehicle body-side rocking shaft and a front end of the crankcase , the second imaginary line (L2) connecting an exhaust pipe connection portion of the cylinder portion , with which an end of the exhaust pipe is connected, and the vehicle body-side rocking shaft , the exhaust pipe includes an upstream side exhaust pipe located upstream of the catalyst unit , characterized in that the upstream side exhaust pipe includes a downward extension portion that extends from the exhaust pipe connection portion downwardly, a lateral extension portion that extends from a lower end of the downward extension portion toward a side opposite from the muffler in the vehicle width direction, and a curved portion that is bent from an outer end of the lateral extension portion toward a side of the muffler and connected to the catalyst unit disposed posterior to the downward extension portion , and the exhaust gas sensor is disposed in the upstream side exhaust pipe at a position inferior to the cylinder portion . <EOS>