A vehicular rear wheel steering device (100) includes a housing (10), a rod (21) being non-turnable with respect to the housing (10) and movably supported in an axial direction of the rod (21), and a conversion mechanism (40) arranged between the rod (21) and the housing (10) to convert a rotation of a rotational drive device (30) to a drive force in the axial direction. The housing (10) includes a tubular first bush (51) disposed at a first end (10a) and a tubular second bush (52) at a second end (10b). Each bush (51, 52) is slidably engaged to an outer periphery of the rod (21) and supports the rod (21) to be movable in the axial direction. A rod supporting rigidity of the first bush (51) is lower compared to that of the second bush (52). The first bush (51) is arranged with an elastic body (51b) that deforms in a radial direction of the rod (21). The second bush (52) is arranged with an inner periphery protrusion (52a) at which the rod (21) tilts.
