Opinion polls predict the Democratic Party of Japan (DPJ), led by Yukio Hatoyama, to put an end to more than 50 years of rein by Prime Minister Taro Aso's Liberal Democratic Party.
Voting booths opened at 7:00am local time (2200 GMT Saturday) and close at 8:00 pm (1100 GMT Sunday), with media exit polls expected immediately afterwards.
Hatoyama has campaigned for change on a platform of social welfare initiatives [Reuters]
Some 103 million Japanese are eligible to vote, with turnout expected to be high.
Al Jazeera's Steve Chao reporting from Tokyo said the last minute surveys indicated that the opposition was still well on its way for a landslide victory.
"There is still a great deal of dissatisfaction among the public with the ruling government and it's ability to govern the country.
"The economy is in the worst state since World War two, unemployment is at 5.7 per cent which means that three and a half million people are unemployed.
"The opposition has been campaigning on an Obama style campaign, promising massive changes, to take on the heavy bureaucracy created by the ruling government largely blamed for the problems of the country.
Chao said that the prime minister had also come out strongly in his last-minute appeal to urge voters "to reconsider and to question whether they could trust the opposition to run the government at a time of economic crisis.
"He has also stressed that he needs more time to implement the massive economic reforms to deal with the global financial crisis.
"Japan is the world’s second largest economy and that's why it matters a lot, not only to the voters down here but to the rest of the world because what happens in Japan is often a bellwether for the health of the world’s financial status."
Opinion poll lead
Surveys in major newspapers, including the Mainichi and the Asahi, said that the Democratic Party of Japan (DPJ) of Yukio Hatoyama was likely to win more than 320 seats in the 480-member lower house of parliament.
Hatoyama travelled to the city of Sakai in western Japan on Saturday where he repeated his call for voters to support change.
"At last, it is the election tomorrow, one that we will be able to tell the next generation changed Japanese history," he said.
The LDP has ruled power for all but 10 months since it was founded in 1955, but the DPJ already controls the less powerful upper house of parliament following elections in 2007.
Under a mantra of "Putting People's Lives First", the DPJ has offered a platform heavy on social-welfare initiatives, including cash handouts for job seekers in training and families with children.
"We will stop bureaucracy-led politics and draft policies through dialogue with the Japanese people," Hatoyama said.
But Jeff Kingston, director of Asian Studies at Temple University in Japan, said that voters seemed set to vote for "change that they don't believe in and for a leader they are not all that crazy about".
"Polls show that only 25 per cent of people actually believe that the DPJ is actually going to lead the country in the right direction," he told Al Jazeera from Tokyo.
"Everybody is so deeply frustrated with the ruling party that they are desperate for change. The vote for the DPJ is not a mandate on their platform; it is just a verdict on the hopelessness of the current situation."
Hatoyama will face tough challenges if he does succeed with the nation suffering its worst unemployment since the second world war and lingering deflation.
