TOKYO — The ailing administration of Japan’s Prime Minister Abe was dealt its heaviest blow so far yesterday when the agriculture minister committed suicide.

Toshikatsu Matsuoka, 62, was found hanged in his Tokyo apartment just hours before he was due to be questioned in Parliament over allegations that he claimed more than $200,000 in expenses already paid for out of the public purse.

The minister had also been linked to firms accused of rigging bids for government contracts, for which he is believed to have received about $110,000 in campaign funds.

The scandal is the latest to overshadow the leadership of Mr. Abe, who had consistently defended the agriculture minister against resignation calls.

Since taking over eight months ago from Prime Minister Koizumi, his charismatic predecessor, Mr. Abe has seen two of his senior officials forced to resign due to mishandling of public money.

Mr. Abe has also stood by other ministers despite high-profile gaffes that dented support. Hakuo Yanagisawa, the health minister, referred to women as “birth-giving machines,” while the education minister, Bunmei Ibuki, said “too many human rights” were bad for the health of society, like consuming “too much butter.”

Critics say Mr. Abe has shown poor judgment in his appointments, compounded by either misguided loyalty or arrogance in sticking by colleagues. As elections to the upper house of Parliament loom in July, a recent poll indicated that fewer than one in three Japanese now support his government.

More than 30,000 Japanese commit suicide each year, one of the highest rates in the world. Its growth during the last decade is linked to the country’s long recession, which has seen rising unemployment and bankruptcy, especially among middle-aged men.

Suicide in ancient Japan, particularly hara-kiri, the ritual cutting open of the stomach, could atone for failure or disgrace. A Japanese book, “The Complete Suicide Manual,” has sold more than 2 million copies in the country since its publication in 1993.