To provide a support device in which grounding can be easily changed, in regard to a support device for a working vehicle which is grounded by selecting a roller or an earth plate.

The support device for the working vehicle comprises: a jack 31 which is attached to a frame 30 of the vehicle and whose tip can be driven to be extensible downward; a link 33 whose one end is journaled to a frame adjacent to the jack; an arm 35 journaling the other end of the link and the tip of the jack and connecting them so that the arm is oscillated around a pivot axis between the arm and the link as a center by the extension/contraction of the jack; the roller 38 capable of rotating and the earth plate 40 capable of oscillating which are arranged at the arm. Positions of the roller and the earth plate which are arranged to the arm are set so as to be in a stored state that the roller and the earth plate are stored when the jack is contracted, so as to be in a roller grounded state where the roller is on the ground during the extension of the jack, and an earth plate grounded state that the earth plate is on the ground in place of the roller when the jack is further extended.