Mechanical timepiece with stud adjustment mechanism

A mechanical timepiece movement comprising:

• a mainspring serving as a power source of the mechanical timepiece;
• a front wheel train rotated by a rotational force produced by the mainspring for driving a time-indicating display;
• and an escapement and speed control apparatus for controlling rotation of the front wheel train and comprising a balance with hairspring for undergoing repetitive rotation in alternating directions, an escape wheel and pinion mounted to undergo rotation based on the rotation of the front wheel train, and a pallet fork for controlling rotation of the escape wheel and pinion based on the repetitive rotation of the balance with hairspring;
• wherein the balance with hairspring has a stud holder rotatably mounted with respect to a central axis of the balance with hairspring, a hairspring holder attached to the stud holder to undergo movement in a direction orthogonal to the central axis of the balance with hairspring, and a hairspring having a central portion fixed to the balance with hairspring and an outer peripheral portion fixed to the hairspring holder so that the hairspring is adjustable by pivoting the hairspring holder.