Seiko is a Japanese watch company that began in 1881. Seiko makes watch with a quartz movement, which requires a battery, and an automatic movement, which is powered by the natural movement of your wrist. Changing a watch battery in a Seiko is an easy process, even if you do not have experience working with watches. When changing a battery yourself, there is a risk that you could damage the watch movement.

Turn your Seiko facedown on a soft cloth to prevent the watch face from getting scratched when you are changing the battery.

Look at the back of the watch case. There are two type of watch backs your Seiko could have. If you see grooves around the outside of the case back, you watch has a "screw back." If you do not see grooves, your watch is a "snap back," which means the case back will pop straight up and does not need to be twisted.

For the "screw back," you will need a watch case opener wrench. Adjust the prongs on the wrench to fit in three prongs around the outside of the case, then tighten the prongs. Twist the wrench handle to the left about one half turn to loosen the case back. Remove the wrench, then loosen the case back completely with your fingers. Lift off the back of the case with your fingers.

For the "snap back," fit the tip of a small screwdriver, the size used to work on eyeglasses, into the crevice where the case back meets the watch case. Wiggle the screwdriver until the case back pops up. You may need to use force, but be careful not to scratch the watch case.

Remove the rubber gasket from around the outside of the inner watch. The rubber gasket ensure that the case is waterproof, and you will need to put it back exactly as you found it before you close the watch case.

Locate the watch battery and slide your screwdriver underneath the battery to remove it. Pull the battery out with your fingers once you loosened it from its position. Take note of which side of the battery was facing up. You will need to put the new battery in the same way. Be careful not to touch any other part of the watch with your screwdriver. You could damage the watch movement.

Put the new battery in the same way you found the old battery. You can use tweezers or your fingertips to put the battery in place. When the battery is in place, turn the watch over to make sure the second hand is moving.

Put the rubber gasket around the outside of the watch just as you found it when you opened the watch case. For the "screw back," place the watch back on the watch and screw it in with your fingertips. For the "snap back," press down on the case back until you hear it "click."