To provide a saddle-riding type four-wheel vehicle capable of being simplified in constitution, while securing volume of a breather device without hindering attaching/detaching property of an air cleaner by utilizing a dead space.

At least a part of a portion located on a rear side of an engine 5 of a vehicle body frame 2 includes right rear frame 12a and left rear frame 12a. At least a part of the air cleaner 20 is arranged between the right rear frame 12a and the left rear frame 12a, and is provided to be attachable/detachable to/from the vehicle body frame 2 in the vertical direction. The breather device 23 is attachably/detachably provided in one of a left sidewall 21g of the air cleaner 20 or a right sidewall 21h on a lower side of the right rear frame 12a or the left rear frame 12a and on an upper side of a power transmission mechanism 17, and includes a volume chamber 24 connected to the engine 5 and the air cleaner 20.