The upper house approved the budget, which is 0.39 percent higher than the existing budget, with majority support from the ruling Liberal Democratic Party, after the lower house approved it on March 1, Efe news reported.
The amount allocated to specific policies and budget items, excluding financing costs, is $644 billion.
Over 40 percent of this, $282 billion, or 1.4 percent more than last year, will be used to cover social security costs, an increase attributed to the country's aging population.
In a bid to increase Japan's diplomatic and military clout, Prime Minister Shinzo Abe's administration also increased defence items and development aid.
Despite the record budget, the government has aimed to improve its fiscal health by taking advantage of what it hopes will be its highest revenues in a quarter of a century, around $498 billion, according to projections for the upcoming fiscal year.