A saddle-riding type vehicle comprising: a vehicle body; a combustion engine fixed to the vehicle body frame structure (FR; and an air intake duct (70, 70a, 70b) which extends rearwardly from a front portion of a vehicle body so as to pass laterally by one side of the vehicle body frame structure in a widthwise direction of the vehicle, and through which incoming wind is supplied as an intake air to the combustion engine, wherein the air intake duct (70, 70a, 70b) comprises: an outer half part and an inner half part divided in the widthwise direction; and an outer side surface, a part of which is exposed to the outside in the widthwise direction, wherein: the air intake duct (70, 70a, 70b) extends so as to be curved downward towards the rear, and extends so as to be curved outward in the widthwise direction, the outer half part and the inner half part are joined to each other such that an inner side end portion of the outer half part and an outer side end portion of the inner half part butt each other, characterized in that: the inner side end portion, on an upper side, of the outer half part includes: a joining portion that butts the outer side end portion of the inner half part; and a projection formed above the joining portion and projecting toward the inner side of the vehicle body beyond the joining portion, the joining portion is covered by the projection from above, an inner surface of the inner half part and an inner surface of the outer half part are formed so as to be flush with each other, and an upper dividing face is disposed inward of an intermediate position, in the widthwise direction, of the air intake duct (70, 70a, 70b). an outer half part and an inner half part divided in the widthwise direction; and an outer side surface, a part of which is exposed to the outside in the widthwise direction, wherein: the air intake duct (70, 70a, 70b) extends so as to be curved downward towards the rear, and extends so as to be curved outward in the widthwise direction, the outer half part and the inner half part are joined to each other such that an inner side end portion of the outer half part and an outer side end portion of the inner half part butt each other, characterized in that: the inner side end portion, on an upper side, of the outer half part includes: a joining portion that butts the outer side end portion of the inner half part; and a projection formed above the joining portion and projecting toward the inner side of the vehicle body beyond the joining portion, the joining portion is covered by the projection from above, an inner surface of the inner half part and an inner surface of the outer half part are formed so as to be flush with each other, and an upper dividing face is disposed inward of an intermediate position, in the widthwise direction, of the air intake duct (70, 70a, 70b). the air intake duct (70, 70a, 70b) extends so as to be curved downward towards the rear, and extends so as to be curved outward in the widthwise direction, the outer half part and the inner half part are joined to each other such that an inner side end portion of the outer half part and an outer side end portion of the inner half part butt each other, the inner side end portion, on an upper side, of the outer half part includes: a joining portion that butts the outer side end portion of the inner half part; and a projection formed above the joining portion and projecting toward the inner side of the vehicle body beyond the joining portion, the joining portion is covered by the projection from above, an inner surface of the inner half part and an inner surface of the outer half part are formed so as to be flush with each other, and an upper dividing face is disposed inward of an intermediate position, in the widthwise direction, of the air intake duct (70, 70a, 70b).