A saddle riding type vehicle comprising an engine having an engine rotary shaft extending in a widthwise direction of a vehicle body, which engine comprises: a crankcase to support the engine rotary shaft; a cylinder block to protrude upwardly from the crankcase; a cylinder head mounted on the cylinder block; a supercharger disposed rearwardly of the cylinder block and operable to supply an intake air to the engine under pressure; and an air intake duct fluid connected with an air intake port of the supercharger and operable to guide an incoming wind, which flows forwardly of the engine, towards the supercharger; in which the air intake port is positioned below an upper end of the cylinder head; characterized in that: the air intake duct passes a lateral space of the cylinder block in the widthwise direction and has a lower end positioned below the cylinder head in the lateral space; and the air intake duct has an inner side surface with respect to the widthwise direction, the inner side face being curved at a position forwardly of the air intake port of the supercharger in a direction inwardly of the vehicle widthwise direction towards a rear; wherein in the cylinder block a first distance is measured from a longitudinal center line of the vehicle body to one side end portion in the vehicle widthwise direction and a second distance is measured from the longitudinal center line of the vehicle body to the other side end portion in the vehicle widthwise direction, the first distance being smaller than the second distance; and the air intake duct is disposed on the one side of the combustion engine; the saddle riding type vehicle further comprising a valve driving force transmitting mechanism to transmit the power of the engine into intake and exhaust valves, the valve driving force transmitting mechanism being disposed on the other side opposite to such side of the engine wherein the air intake duct is disposed. a crankcase to support the engine rotary shaft; a cylinder block to protrude upwardly from the crankcase; a cylinder head mounted on the cylinder block; a supercharger disposed rearwardly of the cylinder block and operable to supply an intake air to the engine under pressure; and an air intake duct fluid connected with an air intake port of the supercharger and operable to guide an incoming wind, which flows forwardly of the engine, towards the supercharger; in which the air intake port is positioned below an upper end of the cylinder head; characterized in that: the air intake duct passes a lateral space of the cylinder block in the widthwise direction and has a lower end positioned below the cylinder head in the lateral space; and the air intake duct has an inner side surface with respect to the widthwise direction, the inner side face being curved at a position forwardly of the air intake port of the supercharger in a direction inwardly of the vehicle widthwise direction towards a rear; the air intake duct passes a lateral space of the cylinder block in the widthwise direction and has a lower end positioned below the cylinder head in the lateral space; and the air intake duct has an inner side surface with respect to the widthwise direction, the inner side face being curved at a position forwardly of the air intake port of the supercharger in a direction inwardly of the vehicle widthwise direction towards a rear; wherein in the cylinder block a first distance is measured from a longitudinal center line of the vehicle body to one side end portion in the vehicle widthwise direction and a second distance is measured from the longitudinal center line of the vehicle body to the other side end portion in the vehicle widthwise direction, the first distance being smaller than the second distance; and the air intake duct is disposed on the one side of the combustion engine; the saddle riding type vehicle further comprising a valve driving force transmitting mechanism to transmit the power of the engine into intake and exhaust valves, the valve driving force transmitting mechanism being disposed on the other side opposite to such side of the engine wherein the air intake duct is disposed.