Abstract: A mirror assembly of motorcycle is disclosed. The assembly comprises an arm mechanism including an arm secured to a handlebar, and a bore on the top end; a mirror mechanism including a threaded hole on a bottom of a connecting member thereof; and a universal joint mechanism including a ring-shaped seat secured to the threaded hole, and a post having a top ball, the ball being substantially enclosed by the mirror mechanism and the seat and pivotably supported on the seat when the post is inserted through the seat into the bore for fastening. The mirror mechanism is operative to either turn freely about the ball on a horizontal plane or turn about the ball on a vertical plane in a limited angle.