The income gap among households reached its widest level ever in 2011, the Health, Labor and Welfare Ministry reported.

The ministry on Friday attributed the expanding disparity mainly to an increase in the number of elderly and single-person households with smaller incomes.

The key parameter for measuring income inequalities, known as the Gini coefficient, came to 0.5536 in the reporting year, up 0.0218 point from the previous study conducted in 2008, before the collapse of Lehman Brothers Holdings Inc. sent the global economy into a tailspin.

A Gini coefficient of 1 expresses maximal inequality, where only one person, theoretically, has all of the income in a society. A coefficient of zero expresses maximal equality, where everyone has exactly the same income.

Social scientists regard a Gini coefficient of 0.4 as the danger point when income inequality could trigger social unrest.

The average annual income per household, excluding social security benefits and payments of social insurance premiums, came to around ¥4.05 million, about ¥400,000 less than in the previous study.

The study is conducted roughly every three years in Japan. The latest version, the 16th of its kind, was carried out in July and August 2011, and 5,021 households in 44 prefectures gave valid responses.

The Tohoku prefectures of Fukushima, Miyagi and Iwate, which were severely hit by the March 11, 2011, earthquake and tsunami, were excluded from the poll.

Yonekura sees wage hikes

Jiji

Firms could be ready to raise wages by spring because business sentiment is likely to improve, Keidanren Chairman Hiromasa Yonekura has suggested.

Most firms will see business confidence pick up after they release earnings reports for the year ending in March, Yonekura, head of Japan’s foremost business lobby, said Friday at a news conference.

Yonekura said most firms feel their earnings are picking up, suggesting that annual income increases would not impose excessive burdens on them. But he added that Keidanren cannot force firms to increase wages and that each business unilaterally decides its salary levels.

In a meeting Thursday with industry minister Toshimitsu Motegi, Yonekura took a positive stance on urging companies to hike wages in Keidanren’s guidelines for management in next spring’s “shunto” wage negotiations.

Also at the news conference, Yonekura said Keidanren will set up a sports promotion committee in November for the 2020 Tokyo Summer Olympics. He added that Toyota Motor Corp. President Akio Toyoda has accepted Keidanren’s request to become head of the new committee.