A structure of a bush bearing includes: a bush on which a groove is formed; and an endless annular-shaped elastic member which is installed in the groove of the bush, and that supports a rack shaft, in which an inner circumferential surface of the bush includes a first inner circumferential surface that is in slide contact with an outer circumferential surface of the rack shaft, which is positioned opposite to a formation position of rack teeth, a second inner circumferential surface that faces the outer circumferential surface of the rack shaft with a gap interposed between the outer circumferential surface and the second inner circumferential surface, and the groove formed in a formation range of the first inner circumferential surface has a depth shallower than that of the groove formed in a formation range of the second inner circumferential surface.