Japan's ruling coalition has won a new two-thirds majority in parliamentary elections seen as a referendum on Prime Minister Shinzo Abe's economic policy.
Japanese media reported that Mr Abe's Liberal Democratic Party (LDP) retained its House of Representatives majority.
The LDP will govern with the Komeito party after the parties won 325 seats out of 475.
Prime Minister Shinzo Abe called the snap vote to secure support for his "Abenomics" economic reforms.
Public broadcaster NHK said the LDP had won 290 seats, with Komeito taking 35.
The main opposition party, the Democratic Party of Japan, won 73 seats, an increase of 11, NHK said.
Mr Abe was elected in 2012 and has tried to revive the economy by raising public spending and printing money.
After an initial burst of growth, Japan slipped back into recession in the second half of this year, which many economists have blamed, at least in part, on an increase in sales tax, from 5% to 8% in April.
The tax increase was legislated by the previous government in 2012 to curb Japan's huge public debt, which is the highest among developed nations.
Mr Abe says he called the election to get a mandate to delay a second increase in the tax to 10%, scheduled for 2015.
"My 'Abenomics' policies are still only half-way done," Mr Abe said on Sunday, adding that his government would not become "complacent".
"I am aware that there are still a lot of people who are still not feeling the benefits. But it's my duty to bring [benefits] to those very people, and I believe this election made that clear."
Analysis: Rupert Wingfield Hayes, Tokyo
Many Japanese were bemused by this election. Most thought it completely unnecessary. Some were angry at the huge waste of money. But Shinzo Abe is nothing if not a canny politician. The turnout may have been a record low, but he got what he needed - a new majority, and four more years in power.
Why he felt the need is still unclear. Some observers think he has been facing stiff resistance to his economic policies from within his own ranks. A big election win will help him crush that resistance.
Others think it a cynical move to lock in four more years before his popularity slips further. Whatever the truth Mr Abe is now the most powerful prime minister Japan has had in many years.
The question now is how will he use that power? He says he is determined to push ahead with difficult and potentially unpopular economic reform. His opponents on the left fear he will use it to push Japan further to the right - to try again to overturn Japan's pacifist constitution, and to further whitewash Japan's historic crimes during World War II.
Japan is the third-largest economy in the world, according to the World Bank, but it has struggled in recent years.
Among his pledges, Mr Abe vowed to help more Japanese women enter and remain in employment by tightening anti-discrimination laws and setting employment targets.
The US hopes Mr Abe will be able to expand Japan's military role, so that it can play a bigger part in their alliance. That challenge to Japan's constitutional pacifism - traditionally opposed by Komeito - is expected to lead to heated debate in 2015.
Voters were choosing who sits in the 475-seat lower house of Japan's parliament, the Diet.
Reports said turnout at polling stations was low due to voter apathy and heavy snowfall in parts of the country. The government said turnout was at just 35%, two hours before polls closed.
Several surveys in recent weeks had pointed to a win for Mr Abe's party.
Observers said this was partly due to the lack of a real political alternative, with the opposition in disarray.
What is Abenomics?
Shinzo Abe's economic policy, launched in 2013, was so wide-ranging that it was named after him. It was designed to help pull Japan out of two decades of deflation and kick-start its stagnant economy.
It involved three main proposals:
- Printing vast amounts of money to boost Japan's purchase of government bonds (monetary policy)
- Sharply increasing government spending to help spur growth (fiscal stimulus)
- Reforming key sectors such as agriculture, healthcare and energy (structural reform).
Economic growth briefly returned, helped by a weaker yen that boosted exporters, but 18 months on, Japan's economy is back in recession, and support for Mr Abe has been dwindling.