What is the voltage in Japan?

Electrical current in Japan is 100 volts. Most appliances made for the U.S., like hair dryers and electric shavers, will work in Japan, but at reduced efficiency. Appliance outlets accept flat, two-pin plugs similar to the U.S. and Canada. If you take a three-pronged appliance, bring along a two-prong adapter, or you can purchase those adapters in Japan at electric appliance shops.

Most U.S.-based electric clocks will not work well, since they time themselves against the frequency of the current: they will lose about 10 seconds per minute. Take along a battery-run clock instead.

See also What should I bring to Japan?