The invention discloses an adhesive tape attaching device which comprises a base, a horizontal movable seat, a vertical movable seat, a horizontal driving device, a vertical driving device, an adhesive tape mounting disc and an adhesive tape attaching mechanism. The horizontal movable seat is horizontally slidably mounted on the base, the vertical movable seat is vertically slidably mounted on the horizontal movable seat, and the adhesive tape mounting disc is mounted on the vertical movable seat; the adhesive tape attaching mechanism comprises a fixing support, guide transitional roller sets, a tape press roller and a blade, and the fixing support is mounted on the vertical movable seat; the guide transitional roller sets are mounted on the fixing support, and a tape guide part is arranged below a lowermost guide transitional roller; the tape press roller is mounted on the fixing support and is positioned under the tape guide part, the blade is mounted on the fixing support, and a vertical surface where cutting edges are located is positioned between a vertical section of a tape press side of the tape press roller and a vertical surface where the axis of the tape press roller is located. The adhesive tape attaching device has the advantages that tapes can be attached onto optional surfaces of packing boxes, so that the packing boxes can be sealed, the tapes can be automatically cut off, and the adhesive tape attaching device is wide in application range.