A washing machine comprising: a cabinet which forms an exterior of the washing machine; a supplementary washing machine having a drawer removably mounted to a lower side of the cabinet, a tub for holding laundry, a drum rotatably mounted in the tub and a lid for introducing the laundry to the tub; characterized in that the washing machine comprises an automatic opening/closing member for slidably opening/closing the lid at the time the supplementary washing machine is opened/closed, in that the lid has a rib (222, 222', 222") projected down from a rear edge of the lid for being pressed by the supplementary washing machine when the supplementary washing machine is closed for returning the lid to an original position, and in that the automatic opening/closing member includes: a plurality of sliding blocks fastened to respective brackets which are fixed to the cabinet, each of the sliding blocks having a slot, wherein the sliding blocks are fastened to opposite sides of the cabinet via the brackets _along opening/closing directions of the supplementary washing machine, a plurality of sliding projections projected from both sides of the lid, wherein the sliding projection is placed in the slot so as to be moveable along the slot when the lid is opened/closed, and a tension spring for elastically supporting the lid with respect to the supplementary washing machine; wherein the tension spring extends when the lid is closed, and returns to an original position when the lid is opened. a cabinet which forms an exterior of the washing machine; a supplementary washing machine having a drawer removably mounted to a lower side of the cabinet, a tub for holding laundry, a drum rotatably mounted in the tub and a lid for introducing the laundry to the tub; characterized in that the washing machine comprises an automatic opening/closing member for slidably opening/closing the lid at the time the supplementary washing machine is opened/closed, in that the lid has a rib (222, 222', 222") projected down from a rear edge of the lid for being pressed by the supplementary washing machine when the supplementary washing machine is closed for returning the lid to an original position, and in that the automatic opening/closing member includes: a plurality of sliding blocks fastened to respective brackets which are fixed to the cabinet, each of the sliding blocks having a slot, wherein the sliding blocks are fastened to opposite sides of the cabinet via the brackets _along opening/closing directions of the supplementary washing machine, a plurality of sliding projections projected from both sides of the lid, wherein the sliding projection is placed in the slot so as to be moveable along the slot when the lid is opened/closed, and a tension spring for elastically supporting the lid with respect to the supplementary washing machine; wherein the tension spring extends when the lid is closed, and returns to an original position when the lid is opened. a plurality of sliding blocks fastened to respective brackets which are fixed to the cabinet, each of the sliding blocks having a slot, wherein the sliding blocks are fastened to opposite sides of the cabinet via the brackets _along opening/closing directions of the supplementary washing machine, a plurality of sliding projections projected from both sides of the lid, wherein the sliding projection is placed in the slot so as to be moveable along the slot when the lid is opened/closed, and a tension spring for elastically supporting the lid with respect to the supplementary washing machine; wherein the tension spring extends when the lid is closed, and returns to an original position when the lid is opened.