PURPOSE: To repeatedly deform a form movable object according to the form of a core member by moving the core member provided in the form movable object by a driving mechanism.

CONSTITUTION: A main switch is turned on. When the prescribed sound volume of sound is detected by a sensor switch 3, a motor 11 is rotated. Since one gear 14 of a driving mechanism (a) consisting of a plurality of gears is engaged with a gear 12 fixed to the output shaft of the motor 11, said driving mechanism (a) is driven and a core member 10 is placed in a stem member 6 composed of a material capable of being deformed and rotated. When a snaking core member 10 is rotated, the stem member 6 moves as if it ripples according to the snaking form, which seems that a form movable object is alive and gives an unexpected feeling and surprise to people to see it.