A shower door assembly, comprising: a horizontal track; a vertical side frame provided on an end with a vertical first opening; a connecting device connecting the horizontal track to the vertical side frame; the connecting device being characterized by comprising: a retaining member retained to an end of the horizontal track and provided with a lug protruding away from the horizontal track; a connecting member provided within the vertical side frame and at a position facing the first opening, having a width larger than that of the first opening, and being provided with a second opening, the lug passing through and extending out of the second opening, wherein the connecting member comprises a hook provided below the second opening and extending into a locking hole of the vertical side frame to restrict movement of the connecting member in a direction perpendicular with the horizontal track; and a locking member provided with a connecting portion hinged to a part of the lug that extends out of the second opening through which the lug passes, the connecting portion being provided with a projection, wherein the locking member is in a locked position when the projection abuts against the connecting member, and is in an unlocked position when the projection is away from the connecting member. a horizontal track; a vertical side frame provided on an end with a vertical first opening; a connecting device connecting the horizontal track to the vertical side frame; the connecting device being characterized by comprising: a retaining member retained to an end of the horizontal track and provided with a lug protruding away from the horizontal track; a connecting member provided within the vertical side frame and at a position facing the first opening, having a width larger than that of the first opening, and being provided with a second opening, the lug passing through and extending out of the second opening, wherein the connecting member comprises a hook provided below the second opening and extending into a locking hole of the vertical side frame to restrict movement of the connecting member in a direction perpendicular with the horizontal track; and a locking member provided with a connecting portion hinged to a part of the lug that extends out of the second opening through which the lug passes, the connecting portion being provided with a projection, wherein the locking member is in a locked position when the projection abuts against the connecting member, and is in an unlocked position when the projection is away from the connecting member. a retaining member retained to an end of the horizontal track and provided with a lug protruding away from the horizontal track; a connecting member provided within the vertical side frame and at a position facing the first opening, having a width larger than that of the first opening, and being provided with a second opening, the lug passing through and extending out of the second opening, wherein the connecting member comprises a hook provided below the second opening and extending into a locking hole of the vertical side frame to restrict movement of the connecting member in a direction perpendicular with the horizontal track; and a locking member provided with a connecting portion hinged to a part of the lug that extends out of the second opening through which the lug passes, the connecting portion being provided with a projection, wherein the locking member is in a locked position when the projection abuts against the connecting member, and is in an unlocked position when the projection is away from the connecting member.