An energy storing device in which energy is stored through spring torsion, comprising: a plurality of cog-wheels, wherein each input end of the cog-wheels is connected with an energy source, which is in the form of a rotational force and the energy output from the cog-wheels is in the form of a torsion; a plurality of torsion magnitude limiting units, connected with the output ends of the cog-wheels, wherein if the magnitude of the torsion exceeds a pre-determined value of the torsion magnitude limiting units, the torsion magnitude limiting units interrupt the torsion by the way of idling to prevent the damage of the energy storing units; a plurality of single-directional input bearings, connected with the output ends of the torsion magnitude limiting units to only allow the single-directional passage of the torsion from each of the torsion magnitude limiting units to the corresponding energy storing set and to prevent the passage of the rotational force in the opposite direction so as to protect the torsion magnitude limiting units and cog-wheels; a plurality of energy storing units, wherein each of the energy storing units includes at least two rotational disc portions, which are connected with each other co-axially, and a leaf spring unit is provided between each pair of rotational disc portions, the two ends of each leaf spring unit are connected with a central retaining portion and a retaining groove and one end of the each leaf spring unit is bent in an opposite direction so as to increase the energy storage efficiency; and a plurality of speed increasing cog-wheels, connected with the output end rotational disc portions, wherein the speed increasing cog-wheels may lock up the rotational disc portions when the speed increasing cog-wheels are inactivated so as to allow the rotational disc portions at the output ends of the energy storing units to rotate and thus store energy and the speed increasing cog-wheels may increase the rotational speed of the output end rotational disc portions to output the energy when the speed increasing cog-wheels are activated. a plurality of cog-wheels, wherein each input end of the cog-wheels is connected with an energy source, which is in the form of a rotational force and the energy output from the cog-wheels is in the form of a torsion; a plurality of torsion magnitude limiting units, connected with the output ends of the cog-wheels, wherein if the magnitude of the torsion exceeds a pre-determined value of the torsion magnitude limiting units, the torsion magnitude limiting units interrupt the torsion by the way of idling to prevent the damage of the energy storing units; a plurality of single-directional input bearings, connected with the output ends of the torsion magnitude limiting units to only allow the single-directional passage of the torsion from each of the torsion magnitude limiting units to the corresponding energy storing set and to prevent the passage of the rotational force in the opposite direction so as to protect the torsion magnitude limiting units and cog-wheels; a plurality of energy storing units, wherein each of the energy storing units includes at least two rotational disc portions, which are connected with each other co-axially, and a leaf spring unit is provided between each pair of rotational disc portions, the two ends of each leaf spring unit are connected with a central retaining portion and a retaining groove and one end of the each leaf spring unit is bent in an opposite direction so as to increase the energy storage efficiency; and a plurality of speed increasing cog-wheels, connected with the output end rotational disc portions, wherein the speed increasing cog-wheels may lock up the rotational disc portions when the speed increasing cog-wheels are inactivated so as to allow the rotational disc portions at the output ends of the energy storing units to rotate and thus store energy and the speed increasing cog-wheels may increase the rotational speed of the output end rotational disc portions to output the energy when the speed increasing cog-wheels are activated.