The ruling Liberal Democratic Party, which has ruled almost continuously for decades, is expected to continue to stay in power.
Technology stocks, banks and a mix of companies that rely on consumer spending accounted for much of the gains.
The Dow Jones Industrial Average rose 0.7% to 35,730.48, leaving it just shy of the all-time high it set on Tuesday.
Investors welcomed another encouraging batch of corporate earnings reports by companies such as Ford and Caterpillar.
economy slowed sharply to a 2% annual growth rate in the July-September period, according to the Commerce Department.
The Labor Department released a more upbeat report on the nation’s unemployment situation.