The invention discloses an unwinding device comprising two supports which are placed vertically. The supports are fixedly connected through a transverse rod. The unwinding device is characterized in that the middle of one of the supports is provided with three rollers, the three rollers are placed in a triangular mode, the lower portion of the other support is provided with a roller, a square pipe is arranged between the two supports, and one side of the square pipe is connected with an electric eye. According to the unwinding device, a plurality of circles of grooves are formed in the surface of the roller body of each roller to prevent shifting of wall paper; the square pipe made of stainless steel materials is arranged between the two supports, one side of the square pipe is connected with the electric eye, when the wall paper sequentially passes through the three rollers and reaches the square pipe, the square pipe makes contact with the wall paper, the surface of the wall paper keeps smooth, the electric eye detects whether the wall paper shifts or not, and if the wall paper shifts, the wall paper is aligned timely. The unwinding device has the advantages of being simple in structure, convenient to use, low in cost and the like.