To assess the food habits and the seasonal differences of nutrient intakes and diet qualities of adult working women aged 30 - 49y in Busan, dietary survey was conducted in summer and in winter by a questionnaire and two-day food record. Anthropometric assessment was also investigated in two seasons. $91.8\%$ of those skipped breakfast in the main. $44.3\%$ had irregular meals. The mean daily energy intake was 1725.8 kcal with $63.3\%$ of energy intake being supplied by carbohydrates, $14.7\%$ by protein, $22.3\%$ by fat in summer and 1598.4 kcal with $62.1\%$ of energy intake being supplied by carbohydrates, $15.6\%$ by protein, $22.1\%$ by fat in winter. Over $70\%$ of iron intake came from plant origin in two seasons. The mean intakes of energy, calcium, iron and vitamin A in summer and energy, calcium, iron, vitamin A and vitamin $B_2$ in winter were below Recommended Dietary Allowance (RDA) for Koreans. As well as insufficiency in iron, the bioavailability of iron is considered to have been low because most of iron intake came from plant origin in two seasons. For calcium and iron in summer and calcium, iron, vitamin A and vitamin $B_2$ in winter, proportions of subjects with intake levels less than $75\%$ of RDA were over $40\%$ in summer and over $50\%$ in winter, respectively. The nutrient adequacy ratios (NAR) were below 0.75 for calcium and iron in summer and calcium, iron, vitamin A and vitamin $B_2$ in winter. NARs of iron (p<0.05), vitamin A (p<0.01) and vitamin $B_2$ (p<0.001) in winter were significantly lower than those in summer. The mean adequacy ratios (MAR), an index of overall dietary quality were 0.85 in summer and 0.80 in winter. The MAR in winter was significantly lower than that in summer (p < 0.05). The indexes of nutritional quality (INQ) were below 1 for calcium and iron in summer and calcium, iron, vitamin A and vitamin $B_2$ in winter. The intake (p<0.05) and NAR (p<0.05) of vitamin $B_2$ showed positive significant correlations with height in winter. In conclusion, nutrient intake and diet quality of adult working women were different between the summer and the winter. So nutritional education programs for summer and winter are needed for adult working women.