Unionized workers at Renault Samsung Motors voted to reject a deal on wages and working conditions that the union reached with the company last week.
Of the two-thousand-219 union members present for Tuesday's vote, 51-point-eight percent voted against the deal while 47-point-eight percent voted in favor.
Last Thursday, the company and union announced that they had reached a tentative deal after eleven months of tough negotiations.
In the deal, the two sides agreed on one million won in compensation for freezing the base pay of each employee and a nine-point-76 million won incentive for each.
Labor and management began negotiations in June of last year but had been in a severe dispute for about eleven months, with unionized workers staging partial walkouts 62 times.