Abstract: A timepiece, whose hands move by mechanical energy of a mainspring transmitted through a wheel train, includes a winding-up portion for accumulating energy in the mainspring, an addition and subtraction wheel train driven by addition and subtraction of accumulated energy corresponding to an amount by which the mainspring is wound up and unwound, respectively, an addition and subtraction wheel, disposed in the addition and subtraction wheel train, that rotates in correspondence with an amount by which the mainspring is wound up and unwound, and a lock mechanism actuated in response to the rotation of the addition and subtraction wheel to limit winding up and unwinding of the mainspring to a selected range of windings of the mainspring. This controls the torque output by the mainspring to a fixed range. The addition and subtraction wheel train allows efficient use of space, and can be incorporated in a watch.