To investigate the ultrasonic effects of progressive resistance exercise (PRE) for the treatment of patients with breast cancer-related lymphedema (BCRL). The 32 patients with diagnosed BCRL were randomly divided into two groups: the PRE group and the non-PRE group. After complex decongestive physiotherapy, PRE was performed by 0.5 kg dumbbell while wearing a compression stocking or a multilayer bandage to avoid aggravation of the lymphedema in the shoulder and arm. In the first week, the PRE group performed five repetitions of each exercise, twice a day, and the exercise were increased to five repetitions every week during 8 weeks. The thickness of muscle and subcutaneous tissue and circumferences of proximal and distal upper limbs were measured at baseline, 4 weeks, and 8 weeks. Examiners measured the circumference of upper limbs with tape measure, then the thickness of the muscle and subcutaneous tissue were measured by ultrasonography. Muscle thickness of the upper limbs was less in the affected limb than that of the nonaffected limb at pretreatment. The thickness of subcutaneous tissue and circumferences of the arm was more decreased in the PRE group than that of the non-PRE group. The thickness of muscle of the arm was more significantly increased in the PRE group than that of the non-PRE group (p < 0.05). For the treatment of patients with BCRL, PRE with complex decongestive physiotherapy did not cause additional swelling, and it reduced arm circumference by decreased subcutaneous tissue thickness and increased muscle thickness.