A vehicular rear wheel steering device includes a housing, a rod being non-turnable with respect to the housing and movably supported in an axial direction of the rod, and a conversion mechanism arranged between the rod and the housing to convert a rotation of a rotational drive device to a drive force in the axial direction. The housing includes a tubular first bush disposed at a first end and a tubular second bush at a second end. Each bush is slidably engaged to an outer periphery of the rod and supports the rod to be movable in the axial direction. A rod supporting rigidity of the first bush is lower compared to that of the second bush. The first bush is arranged with an elastic body that deforms in a radial direction of the rod. The second bush is arranged with an inner periphery protrusion at which the rod tilts.