A device for applying lengths of adhesive coated tape from a supply length of tape to seal boxes driven along a path past the device. The device includes an application roller initially positioned in the path and supporting an end of the tape for contact by a box to adhere the tape to its leading surface. The application roller is mounted so that, subsequent to such contact, it will be revolved against the bias of a spring and will roll over tape being pulled from the device to press the tape against the surfaces of the box as the box is driven further along the path. Cam and ratchet mechanisms operated by movement of the application roller manipulate a pinch roller (1) to engage the tape closely adjacent its terminal end and hold the tape against the application roller prior to contact of the tape by a box, (2) to move around a longitudinal edge of the tape being applied and re-engage the tape on the application roller in advance of the portion of the application roller adjacent the box subsequent to engagement of a box with tape on the application roller and before a knife on the device severs the tape between the application roller and the box, and (3) to hold the tape against the application roller as the spring returns the application roller to its initial position subsequent to operation of the severing means, while the pinch roller moves along the tape on the application roller to its original position closely adjacent the newly severed end of the tape.