The large influx of women into the labor force is keeping salaries of women at depressed levels and widening the earnings gap between the sexes, a revised study by the Department of Labor reveals.

The study, "The Earnings Gap Between Women and Men," issued recently by the Women's Bureau, says that women who worked at year-round, full-time jobs in 1977 earned only 59 cents for every dollar earned by men. (The Labor Department defined year-round, full-time work as 50 to 52 weeks of 35 hours or more a week.)

"Men's median weekly earnings exceeded women's by $116, so that women had to work nearly nine days to gross the same earnings men grossed in five days," the report said.

It attributed the ever-persistent male-female earnings gap to two primary factors.

"First, despite the fact that increasing numbers of women are securing higher-level and better-paying positions, the majority are still concentrated in lower-paying occupations of a traditional nature that provide limited opportunity for advancement," it said.

"Second, the recent dynamic rise in women's labor-force participation has resulted in larger proportions of women who are in or near the entry levels."

Over the last 20 years, the percentage of all women 16 and older who are in the labor force has increased steadily until women in 1978 accounted for 42 percent of the civilian work force.

"Many of the new entrants as well as re-entrants to the labor-force must often accept relatively-low-paying jobs, which tend to pull down their median earnings," the report said. "However, the earnings of many of these women may increase over time, especially for those in nontraditional careers."

Discrimination in hiring, promotions, and pay scales continues to be a major obstacle to equality for women in the workplace, according to the study.

Regionally women generally fared best in the Northeast, where their income was 62 percent of men's.