To provide a steering device for facilitating suitable steering operation required for an agricultural working machine.

A steering operation tool 42, a driving means for a gentle turn, and a driving means for a steep turn are interlocked so as to make the gentle turn performed by the dual drive for decelerating one traveling device to the same direction of the other traveling device in gentle turn operation zones Ls, Rs on a side near the neutral position out of a plurality of operation zones of the steering operation tool 42, and so as to make the steep turn performed in steep turn operation zones Lb, Rb on the outside. In the gentle turn operation zones Ls, Rs, as a distance from the neutral position gets longer, the turning function gets better, and the operation range is set to be larger than operation ranges of other operation zones. Further, a turning mode selecting means is provided for selecting a first turning mode for performing the steep turn by the operation to the steep turn operation zones Lb, Rb or a second turning mode for not operating the driving means for the steep turn regardless of the operation to the steep turn operation zones Lb, Rb.