A saddle-riding vehicle which comprises: a pair of left and right main frames, with respect to a vehicle traveling direction, extending rearwardly from a head pipe in the vehicle traveling direction; a front cowl covering an area forwardly of the head pipe, with respect to the vehicle traveling direction; an air cleaner disposed between the left and right main frames and above an engine; a front fork pivotally supported by the head pipe, and; an air intake duct configured to introduce an incoming wind through an inlet port at a front end thereof and to then supply it to the air cleaner, wherein the air intake duct includes: a duct front portion disposed forwardly of the head pipe, with respect to the vehicle traveling direction, and the front fork; a duct intermediate portion extending from the duct front portion in a rearward direction, with respect to the vehicle traveling direction, along a vehicle widthwise lateral outer area of the front fork and the main frames; and a duct rear portion curved from the duct intermediate portion in a direction inwardly of a vehicle widthwise direction and terminating in communication with the air cleaner, the inlet port of the air intake duct confronts an air introducing opening that is open forwardly of the front cowl, with respect to the vehicle traveling direction, the duct front portion is curved rearwardly, with respect to the vehicle traveling direction, from the inlet port at the front end so as to extend towards a vehicle widthwise direction lateral outer side, a portion of an inner wall surface of the duct front portion constitutes an attachment portion with which the air introduced through the inlet port collides to allow a water component to be attached thereto, characterized in that the inlet port of the air intake duct is positioned on a vehicle widthwise direction center line of the vehicle, the attachment portion has a transverse sectional shape which extends straight in a direction inclined rearward relative to the vehicle widthwise direction, and the attachment portion is positioned on the vehicle widthwise direction center line. a pair of left and right main frames, with respect to a vehicle traveling direction, extending rearwardly from a head pipe in the vehicle traveling direction; a front cowl covering an area forwardly of the head pipe, with respect to the vehicle traveling direction; an air cleaner disposed between the left and right main frames and above an engine; a front fork pivotally supported by the head pipe, and; an air intake duct configured to introduce an incoming wind through an inlet port at a front end thereof and to then supply it to the air cleaner, wherein the air intake duct includes: a duct front portion disposed forwardly of the head pipe, with respect to the vehicle traveling direction, and the front fork; a duct intermediate portion extending from the duct front portion in a rearward direction, with respect to the vehicle traveling direction, along a vehicle widthwise lateral outer area of the front fork and the main frames; and a duct rear portion curved from the duct intermediate portion in a direction inwardly of a vehicle widthwise direction and terminating in communication with the air cleaner, the inlet port of the air intake duct confronts an air introducing opening that is open forwardly of the front cowl, with respect to the vehicle traveling direction, the duct front portion is curved rearwardly, with respect to the vehicle traveling direction, from the inlet port at the front end so as to extend towards a vehicle widthwise direction lateral outer side, a portion of an inner wall surface of the duct front portion constitutes an attachment portion with which the air introduced through the inlet port collides to allow a water component to be attached thereto, characterized in that the inlet port of the air intake duct is positioned on a vehicle widthwise direction center line of the vehicle, the attachment portion has a transverse sectional shape which extends straight in a direction inclined rearward relative to the vehicle widthwise direction, and the attachment portion is positioned on the vehicle widthwise direction center line.