A body structure of a saddle riding vehicle comprising: a head pipe; and a pair of left and right main frames that extend diagonally from the upper rear side of the head pipe to be branched to left and right sides and disposed more downward as they go outward in a vehicle width direction and then curved to change orientation to extend downward; and one down frame extending downward from the head pipe, a pair of left and right side gussets that are branched to the left and right sides from an outer portion of the head pipe and that are connected to the pair of left and right main frames and the down frame so as to bridge over a space between front lower sections of the left and right main frames and an upper section of the down frame, the left and right side gussets including rear side sections formed in a convex arc shape toward the head pipe when seen in a side view and curved upward when seen in a front view, said side gussets include front sections extending diagonally and vertically along a central axis of the head pipe, upper side sections extending along the main frames (21L, 21R) to bridge the upper ends of the front side sections and the upper ends of the rear side sections, and lower side sections extending along the down frame to bridge the lower ends of the front side sections and the lower ends of the rear side sections, wherein an internal space in which a vehicle component is disposed is formed between the pair of left and right side gussets in a vehicle width direction, an opening section opened in a forward/rearward direction is formed in the side gusset, and an opening section-side flange curved inward in the vehicle width direction towards the internal space is formed at an outer circumferential edge of the opening section of the side gusset so as to guide a traveling air towards the vehicle component installed in the internal space. a head pipe; and a pair of left and right main frames that extend diagonally from the upper rear side of the head pipe to be branched to left and right sides and disposed more downward as they go outward in a vehicle width direction and then curved to change orientation to extend downward; and one down frame extending downward from the head pipe, a pair of left and right side gussets that are branched to the left and right sides from an outer portion of the head pipe and that are connected to the pair of left and right main frames and the down frame so as to bridge over a space between front lower sections of the left and right main frames and an upper section of the down frame, the left and right side gussets including rear side sections formed in a convex arc shape toward the head pipe when seen in a side view and curved upward when seen in a front view, said side gussets include front sections extending diagonally and vertically along a central axis of the head pipe, upper side sections extending along the main frames (21L, 21R) to bridge the upper ends of the front side sections and the upper ends of the rear side sections, and lower side sections extending along the down frame to bridge the lower ends of the front side sections and the lower ends of the rear side sections, wherein an internal space in which a vehicle component is disposed is formed between the pair of left and right side gussets in a vehicle width direction, an opening section opened in a forward/rearward direction is formed in the side gusset, and an opening section-side flange curved inward in the vehicle width direction towards the internal space is formed at an outer circumferential edge of the opening section of the side gusset so as to guide a traveling air towards the vehicle component installed in the internal space.