A one-piece tape cutting device is provided, comprising: a tape shaft, a tape pressing part, a cutting part, a tape supporting part, a side plate, and a pressing plate, and all are integrally formed without being connected by any fasteners. the tape is sleeved on the outside of the tape shaft from the opposite side of the side plate, the pressing plate is stretched by the tape and away from the tape shaft, so that the tape is pressed by the pressing plate and does not rotate, the tape is restricted by the anti-dislodging piece and does not disengage, and the end of the tape is pulled through the gap between the tape supporting part and the tape pressing part, and non-adhesive surface of the tape faces the tape pressing part, and the cutting part can cut through the tape.