To provide a method capable of simplifying the structure of an adjust assembly and effectively and inexpensively adjusting the frequency of a spring balance.

In order to adjust the oscillation frequency of the spring balance, in a first step, the balance spring is manufactured with elastic torque larger than the reference torque corresponding to the reference frequency of the oscillation frequency of the adjust assembly. After the spring balance is assembled, the spring is machined by a laser bean to decrease the elastic torque until the elastic torque substantially reaches the reference elastic torque. To be concrete, laser machining removes material to reduce the height of the balance spring in a certain area, or reduce the thickness of a strip for forming the balance spring. According to this method, the conventional adjusting means, especially a pin with index can be omitted. Thus, the operational error of a clock as a function of position can be prevented.