Toyota, the world's best-selling brand, depreciated 3.7% at the opening of the Tokyo stock exchange.
Shares of major Japanese automakers fell more than 3% on Thursday after U.S. President Donald Trump announced a 25% tariff on imported vehicles effective April 2.
The Republican added to his tariff list with fees on "all cars not made" in his country.
In Japan, that industry is one of the great pillars of the economy, with 10% of jobs linked to the sector.
Toyota, the world's best-selling brand, depreciated 3.7% at the opening of the Tokyo stock exchange. Nissan fell 3.2%, Honda dropped 3.1% and Mitsubishi Motors also decreased by 3.7 percent.
In South Korea, Hyundai's shares plummeted 3.4 percent.
Vehicles accounted for approximately one third of the 21.3 trillion yen (142 billion dollars) of Japanese exports to the United States in 2024.
The president of the Japan Automobile Manufacturers Association, Masanori Katayama, warned weeks ago that U.S. tariffs "will have a negative overall impact on the economies of the United States and Japan."
Ministers from the Asian country have pressured their American counterparts for exemptions from tariffs on products such as steel and cars, but their requests have been denied.
