Some owners of the third-generation Prius have complained that on bumpy roads and ice, the brakes seem to slip and the car lurches forward before the traditional brakes engage.
"Let me assure everyone that we will redouble our commitment to quality as a lifeline of our company", Toyoda told a news conference in Tokyo.
"With myself taking the lead, and by keeping to the 'genchi genbutsu' principle, all of us at Toyota will tackle the issue in close cooperation with dealers and suppliers together, we will do everything in our power to regain the confidence of our customers," he said, first in Japanese, then in English.
Genchi genbutsu, meaning "go and see", is one of the five principles in Toyota's much-emulated management and production philosophy.
(Additional reporting by Mayumi Negishi, Elaine Lies and Linda Sieg in TOKYO; Toshi Maeda in TOYOTA CITY; David Bailey and Bernie Woodall in DETROIT; Steve Gorman in LOS ANGELES; John Crawley in WASHINGTON, Jungyoun Park in SEOUL and Helen Massy-Beresford in PARIS; Writing by Lincoln Feast; Editing by David Cowell)