Fumio Kishida has been re-elected as Japan's prime minister, after his governing party scored a major victory in key parliamentary elections.

Elected just over a month ago by parliament, Mr Kishida called a quick election in which his governing party secured 261 seats in the 465-member lower house, the more powerful of Japan's two-chamber legislature, enough to maintain a free hand in pushing legislation through parliament.

The October 31 victory increases his grip on power and is seen as a mandate from voters for his weeks-old government to tackle the pandemic-battered economy, virus measures and other challenges.

Mr Kishida said he saw the results as a signal that voters chose stability over change.

Later Wednesday he will form his second Cabinet by keeping all but one of the ministers he appointed when he took office on October 4, and then map out his economic measures and other key policies at a news conference.

Mr Kishida had been chosen by the Liberal Democrats as a safe, conservative choice a month ago.

They had feared heavy election losses if the unpopular Yoshihide Suga had stayed in power.

Mr Suga resigned after only a year in office as his popularity plunged over criticism of his handling of the coronavirus pandemic and his insistence on holding the Tokyo Olympics despite concerns of a virus surge.

The better-than-expected election results may give Mr Kishida's government more power and time to work on campaign promises, including Covid-19 control, economic revitalisation and strengthening Japan's defence capability.

Mr Kishida has stressed the importance of a stronger military amid worries over China's growing power and influence and North Korea's missile and nuclear threats.

He has opposed changes to a law that requires married couples to adopt a single surname, which forces most women to abandon their maiden names.

The Liberal Democrats are widely seen as opposed to gender equality and diversity.