Watches can be adversely affected by magnetism and may gain or lose time.
It is important not to leave a watch close to magnetic objects for a long periods.

Nowadays, we are surrounded by many magnetic products.
In particular, smartphone or cell phones (speaker), television and PC or tablet device speakers,
handbag clasps, magnetic cover of tablet device, hair-driers, electric razors, these are all magnetic. 

The magnetism caused by these products can easily affect the parts in the watch movement.
Keeping your watch more than 5 cm away from magnetic products weakens the influence of magnetism.

When you suspect your watch has been influenced by magnetism,
contact the nearest Authorized Seiko Service Center to have the watch demagnetized.

Analogue Quartz:

Analog quartz watches utilize the power of magnetic force in order to drive the step motors to move the rotors.
These step motors are extremely small and may easily be affected by magnetism and this may impact the rotor.
As a result, watches may stop or fail to keep correct time.
But magnetism remaining inside of the watch does not affect its accuracy, so keep it away from magnetic products more than 5 cm and reset the correct time.
If the watch has been influenced by an extremely strong magnetic force, be sure to have it demagnetized.

Spring Drive:

Spring Drive watches utilize the power generated from the mainspring while the speed is controlled by a regulation mechanism.
Once the rotor used in this regulation mechanism is affected by magnetism, it causes a gain or loss of time and influences its accuracy.
But magnetism remaining inside of the watch does not affect its accuracy, so keep it away from magnetic products more than 5 cm and reset the correct time.
If the watch has been influenced by an extremely strong magnetic force, be sure to have it demagnetized.

Mechanical:

A mechanical watch affected by magnetism remains magnetized even after being separated from magnetic products.
If the hairspring gets magnetized, the oscillation of the balance will be unstable and this may cause a gain or loss of time and influence its accuracy.
Be sure to have it demagnetized in order to improve accuracy.

Digital Quartz:

In general, magnetism has no effect since there are no motors in digital watches.

Table of phenomenon and solution for each drive system

Drive System

Phenomenon by magnetism

Solution

by DC

by AC

Analog quartz watch

Stoppage

Hand rotates quickly

Move away from the magnetic products
and reset the correct time.

Spring Drive

Delay

Advance

Mechanical watch

Delay or Advance

Delay or Advance

If the accuracy does not recover, demagnetization and overhaul is required.

Digital quartz watch

No influence

No influence