Abstract: A magnetic adhesive tape holder includes an upper housing and a lower housing movably received in the upper housing. Two first resilient members are provided between the upper and lower housings to give the lower housing a tendency to move away from the upper housing. A clamping member is formed on the upper housing and extends into the second housing. The clamping member is in an open status when the upper housing is not pressed towards the lower housing, and in a closed status when the upper housing is pressed towards the lower housing. A first gear and a second gear are rotatably mounted on the second rear wall and engaged with each other. A cutting member is mounted on the second rear wall and beneath the first gear. A roll of magnetic adhesive tape provided in the holder can be automatically and easily cut off with a determined length.