An object of the present invention is to provide a supporting mechanism that enables an exhaust treatment device to be disposed in a position as low as possible so that rearward visibility may be improved in a work vehicle in which the exhaust treatment device is disposed above the engine. A supporting mechanism according to a first aspect of the present invention supports a first exhaust treatment device and a second exhaust treatment device for treating exhaust gas from an engine and is provided with a base member, a first supporting member, and a second supporting member. The base member includes a first connecting part, a second connecting part, a first pipe member, and a second pipe member. The base member supports the first exhaust treatment device and the second exhaust treatment device. The first supporting member supports one side of the base member. The second supporting member supports the other side of the base member. The first connecting part is joined with the first supporting member. The second connecting part is joined with the second supporting member. The first pipe member and the second pipe member are disposed side by side on an identical horizontal plane. An opening section is formed by the edges of the first pipe member, the second pipe member, the first connecting part, and the second connecting part.