A toy with an exterior structure. Constructed to transform from a rollable first shape to a second shape. An interior structure inside the exterior structure is endowed with a magnetic body that moves by way of a magnetic force that acts from the exterior of the toy, an interior locking portion that moves simultaneously with the movement of this magnetic body, and a biasing member that effects a force which moves or turns this interior locking portion in a particular direction. If the magnetic force does not act from the exterior of the toy, the first shape of the exterior structure maintained. In the event that a magnetic force has acted from the exterior of the said toy, the exterior structure transforms from the first shape to the second shape.