Democratic Party of Japan leader Katsuya Okada said Tuesday the main opposition party plans to submit to the regular Diet session a bill to lower the minimum age of people running for elections.

Speaking at a news conference a day after the Diet convened the 150-day session, Okada said the DPJ will discuss specific rates of reduction, but that the party intends to include the idea in its pledges for the House of Councilors election this summer.

"The minimum age of candidates should be lowered," he said, citing similar instances in other countries.

According to the Public Offices Election Law, candidates must be at least 25 years old to run for House of Representatives, mayoral, town and village head elections, and at least 30 years old to run for Upper House and prefectural governorship elections.

"It is strange that young people in their 20s cannot become prefectural governors or Upper House members," Okada said.

"Prime Minister Shinzo Abe said (this year) is a year of challenge, but I would like to stress that this is a year for young people."

In the wake of last year's revision to the law to lower the minimum voting age to 18 from 20, Chief Cabinet Secretary Yoshihide Suga has referred to the need to consider lowering the minimum age of candidates.