supported by a bracket 2 which is fixed to a body 1 of an automobile the bracket 2 has guide bars 3 and 3 39 which pass through the electric powered reducer 1 for mounting the reducer 1 thereon the reducer 1 engages a receiving member 5 by means of a rail 2 39 the receiving member 5 is securely fixed to the inner face of a sliding door b and has horizontally extending upper and lower support plates 6 for receiving a roller chain 4 therebetween each of the support plates 6 is provided with elongated bores 7 and 7 39 at each end thereof the roller chain 4 is moveably mounted between the upper and lower support plates 6 by means of hinge member 8 and 8 39 and movable in the left right direction one hinge member 8 is supported in a bush 9 and has a connection portion 10 to which is connected a wire roped the wire rope d is connected to a lock c a sprocket gear 11 is connected to the reducer 1 with this arrangement the roller chain 4 is moved by the sprocket gear 11 causing the sliding door to be opened a numeral 12 denotes a sensing switch 13 bevel gear 14 support member 15 worm gear and 15 bolts in operation see fig3 a switch or button not shown is on with the sliding door closed to drive the electric powered reducer 1 with the driving of the electric powered reducer 1 the sprocket gear 11 rotates clockwise causing the roller chain 4 to move the bush 9 as shown in fig4 simultaneous with the movement of the bush 9 the connection portion.