Maskawa, 68, was one of three physicists to share the prestigious award announced on Tuesday for his groundbreaking work on fundamental particles.

But his wife, Akiko, said that Maskawa does not travel overseas and feels "quite allergic to trying to speak English."

"And if he needs to go to the award ceremony, he'll need first to apply for a passport," she said at her home in the western city of Kyoto, where Maskawa is a professor of theoretical physics at Kyoto Sangyo University.

Maskawa, bespectacled with grey hair, charmed reporters after the prize was announced by trying to conceal his shyness, at one point sobbing and at another moment forcing such a grin that he stuck out his tongue.

He also raised his arms over his head and said to eager reporters, "You'd like me to do this to show I'm happy, right?"

He earlier told reporters abruptly that he was "not that happy" about receiving the Nobel Prize, which will be handed out at a ceremony in Stockholm on December 10.

"It's just a society party," he said.

But he backtracked on Wednesday.

"I play the devil's advocate, so when somebody tells me to look left, I look right," he said with a big smile.