The purpose of this study was to assess for re-breeding concentrate period in postpartum in milking cows. The 48 cows aged 3.5～5.5 years and of 400～600 kg body weight were examined every 3rd day from 15 to 36 day postpartum. Blood samples for progesterone and estradiol 17 β hormone analyses were withdrawn from the coccygeal vein every third day until the end of the experiment. The ovarian follicular numbers were verified and measured using a multi frequency probe. The least squares means are presented for each day by GLM of SAS. The results showed that ovary lengths (right ovary; 1.64±0.62 cm, left ovary; 1.44±0.46 cm) were similar in right and left ovary activity level during estrous cycle of postpartum cows. We were judged completed uterus on day at 2.31±0.17 cm level of cervix diameter. And we were monitoring started at 6.44±2.03 cm from day 15 after postpartum. The results showed that mean plasma concentration of progesterone (3.28 ng/ml) in large follicle gradually increased days 30 in postpartum. And, monitoring of estradiol 17β (22.18 pg/ml) hormone during postpartum period would be useful to predict the ovarian and uterus activity for re-breeding in postpartum milking cows. From these results, we conclude that cervix diameter (mean: 2.31 cm) was very important for reproductive organ recovery standard level of postpartum milking cows, hormone secretion level (P4: 3.28 ng/ml, E2: 22.18 pg/ml) and body condition score (2.5～2.75) level about 30 days in postpartum period.