This experimental study compares the effectiveness of Automatic Uterine Massage Machine (AUMM) and Manual Uterine Massage on uterine contraction intensity and the amount of postpartum blood loss within two hours after delivery. The participants consisted of 60 postpartum women who were within 2 hours of their normal delivery at Phramongkutklao Hospital, Bangkok, Thailand. The experimental and comparison groups each consisted of 30 participants allocated by a simple random method when visiting the labour room. The comparison group received a manual uterine massage by a nurse, while the experimental group received AUMM. Both groups received standard postpartum care, which included assessment for postpartum hemorrhage, administration of oxytocin 10 units, and ensuring an empty bladder. Mann-Whitney U test was used to analyze the difference in uterine contraction intensity and amount of postpartum blood loss between the groups. The participants’ characteristics between the groups revealed no statistically significant differences (p > 0.05). The manual uterine massage group exhibited significantly stronger uterine contractions compared to the AUMM group (p < 0.001). The key findings indicated that there was no significant difference in the amount of blood loss during the first 2 hours after delivery between the two groups (p = 0.323). Although using AUMM resulted in a significantly lower uterine contraction intensity, the amount of postpartum blood loss was not significantly different compared to the manual uterine massage group. Therefore, AUMM could be an alternative to manual uterine massage, especially in healthcare facilities facing a shortage of nursing staff, particularly during the critical period of the first 2 hours after delivery.