A bag opening and resealing device is formed of a longitudinally elongated body member having a longitudinally extending bag-receiving slot that extends from one end of the body, where the slot is flared to facilitate entry of a bag to be cut, and terminates inwardly of the opposite end of the body. Perpendicular to the slot, the body is provided with a guide slot which terminates inwardly of the opposite ends of the body and extends transversely through the body, and a knife holder is received slidably in the guide slot and mounts a knife blade in position to intercept the bag-receiving slot, wherein, with a bag contained in the bag-receiving slot, movement of the knife holder along its guide slot effects cutting of the bag. Further, with a bag received within the bag-receiving slot, the body may be rotated in order to wrap a portion of the bag tightly about the body member where it is secured in its tightly wrapped, sealed condition by an elastic band stretched over the roll and secured to opposite ends of the body member to prevent loosening or unwinding of the bag on the base member.