Mechanical timepiece

A mechanical timepiece comprising:

• a spring;
• a balance configured to be driven by power from the spring;
• an oscillation circuit configured to output a clock signal;
• a speed governing mechanism including a permanent magnet and a coil, one of the permanent magnet and the coil being held by the balance;
• an external magnetic field detection mechanism configured to detect an external magnetic field by the coil;
• a vibration detection mechanism configured to detect vibration of the balance and output a vibration detection signal;
• a speed governing control mechanism configured to output a drive pulse in accordance with a result of comparison between the clock signal and the vibration detection signal, output a current to the coil by the drive pulse to generate an electromagnetic force, and cause the generated electromagnetic force to act on the permanent magnet to perform processing for governing the balance;
• a power storage mechanism configured to store electric energy to be supplied to the speed governing control mechanism;
• and
• a generator configured to generate the electric energy,
• wherein the speed governing control mechanism is configured to change a processing content of the speed governing of the balance in accordance with a result of the detection of the external magnetic field.