Components of cholesterol, glucose, minerals (selenium, Ca, p) and vitamin E in blood and milk were collected and analyzed weekly after calving from a total of 78 Holstein cows. In this study, we examined changes of chemical components, correlations among them, and factors affecting the changes. The results were summarized as follows; 1 Average levels of components in blood during 9 weeks after calving were 178.8 mg/dl, 62.3 mg/dl, 8.9 mg/dl, 7.4 mg/dl, 52.2 ng/ml, $10.3{\mu}g/ml$, 16.3 mg/dl, 15.3 ng/dl, and 15.8 mg/dl for cholesterol, glucose, Ca, P, selenium, vitamin E, BUN (blood urea nitrogen), MSe (milk selenium), and MUN (milk urea nitrogen), respectively. 2. The levels of cholesterol, glucose selenium, vitamin E and MSe tended to increase over time after calving. 3. The estimated correlations among components were negative(-) for cholesterol and p, positive for selenium, and BUN and also positive for BUN and MUN. Glucose showed positive correlations with P and MSe. 4. For factors influencing the changes of components, there were significant differences in glucose and selenium for age, in selenium and vitamin E for parity, in glucose and MSe for milk and in all components except Ca and selenium for feeding grass and hay, respectively. In urea nitrogen, age and parity only showed significant difference in MUN. In conclusion, the results were suggested that changes of blood and milk components depend on feeding during the postpartum. Especially, we could ascertain that selenium in blood and milk is the important factor for the dairy cows after parturition.