About 30% of the Cargo Truckers Solidarity union were on strike, demanding pay increases given the surge in fuel prices, the country's transport ministry said.
South Korean President Yoon Seok-yeol on Thursday warned strikers not to use violence and said the government is trying to resolve the situation through dialogue.
A South Korean auto industry group called the strike "extremely selfish", saying it would further pressure the sector which has been hurt by the global chip shortage.
Hyundai Motor Co has seen some disruption to production at plants in Ulsan as truck drivers refuse to deliver components to Hyundai's plants, Yonhap news agency reported.
Hyundai Motor declined to comment on the matter.
(Reporting by Heekyong Yang and Ju-min Park; Editing by Edwina Gibbs)
