About 1 out of 5 workers at South Korea's biggest companies is female, and the rate has slightly increased over the past five years, data showed.

The number of workers at the nation’s 100 top-selling companies reached 747,190 as of the end of last year, according to figures released by the Financial Supervisory Service. Among them, 149,568 employees, or about 20 per cent, were female.

Lotte Shopping, the nation’s No. 2 retailer, had the highest ratio of female employees, employing 16,438 women, about 66 per cent of all employees.

Cosmetics companies generally have high rates of female employees exceeding 50 per cent. Distribution companies such as E-mart and Lotte Himart also have high proportions of female employees as well as airliners and banks. Hana Bank tops in the number of female employees among financial companies with 62.3 per cent, followed by KB Kookmin Bank, Woori Bank and Shinhan Bank with 47.1 per cent, 46.6 per cent and 42.3 per cent, respectively.

However, automobile, shipbuilding and steelmaking companies hire few women, around 5 per cent of their workforces on average.

Samsung Electronics, with the largest number of employees of 90,700, is 27.1 per cent female. The overall ratio of female employees in the workforce slightly increased by 1.6 per cent from 17.9 per cent in late 2007. Experts say the slight increase in the number of female workers is partly due to delayed marriage and childbirth among young working women.