The president of Toyota apologized at a hastily arranged news conference Friday night for the quality problems that led to the recall of more than nine million cars worldwide. He also pledged that the Japanese automaker would soon announce steps to address brake problems on the 2010 Prius.

Akio Toyoda, grandson of Toyota’s founder, spoke in his first formal remarks since the uproar enveloping his company, the world’s largest automaker, and took personal responsibility for the problems.“I deeply regret that I caused concern among so many people,” Mr. Toyoda said. “We will do our utmost to regain the trust of our customers.”Asked whether Toyota had underestimated the situation, Mr. Toyoda said, “I believe what is happening now is a very big problem. We are in a crisis.”

Mr. Toyoda also apologized to shareholders for the fall in the company’s share price. The company’s stock has dropped about 20 percent in the last two weeks. Mr. Toyoda said a committee would be set up to look at quality issues. With his comments, he became the second successive Toyota president to apologize for defects on the company’s cars — and the second to assemble a committee to address them.

In 2006, his predecessor, Katsuaki Watanabe, shocked onlookers by bowing low at a news conference and vowing Toyota would improve its quality. But many cars involved in the two recent recalls, one for sticking accelerator pedals, the other for floor mats that could become entangled in the pedals, went on sale after that effort.

One car now in question is the 2010 Prius, the newest version of Toyota’s most important car. The automaker said it was working on a solution to fix issues with the car’s anti-lock brakes, which were redesigned for the 2010 model. Toyota has sold just over 300,000 of the new Priuses in Japan, the United States and Europe since it was introduced.

Company executives also are looking at two other hybrids with the same brake system, the Lexus HS250h and the Sai, a small hybrid sold only in Japan. Mr. Toyoda is among the industry’s best-known executives, but he has been conspicuously absent in recent weeks, even as his company struggled on three continents to contain the fallout of problems that have shaken its long-held reputation for quality.

Until Friday, Mr. Toyoda’s only public comments came in a brief interview with a Japanese broadcaster on the sidelines of the World Economic Forum in Davos, Switzerland. Toyota’s slowness in addressing its problems has been criticized by regulators in the United States and Japan. Earlier this week, Transportation Secretary Ray LaHood spoke with Mr. Toyoda, after sending officials from Washington to Japan in December.

“Users are noticing defects and there have been accidents,” Japan’s transport minister, Seiji Maehara, said Friday ahead of Mr. Toyoda’s briefing. “This leads me to believe Toyota has not put consumers first.” Mr. Toyoda, who spoke in Japanese and English during the news conference, said that was not the case. “I came out here today because I would not want our customers to spend the weekend wondering whether their cars are safe,” he said.

He would not answer a question about whether the company has ever withheld information related to safety concerns. “Toyota is committed to safety,” he said. He added in broken English: “The people who drive Toyota, who cares about Toyota, I’m a little bit worried while they are driving, they feel little bit cautious. But believe me, Toyota’s car is safety but we will try to increase our product better.”