Purpose: The purpose of this study was to investigate urine protein excretion and the effect of muscle strengthening in patients with renal disease. Subjects: Twenty-eight patients (18 to 87 years old) with acute onset renal disease were treated with steroids at the Hospital of Shiga University of Medical Science. Maximum quadriceps force was measured, and 20-minutes sessions in resistance training were started. After 5 weeks, maximum quadriceps force was measured again. Results: Quadriceps force showed no significant difference between before and after intervention. There was negative correlation between mean urinary protein excretion and amount of change in quadriceps force over the 5 weeks (r=-0.40, p=0.038). Conclusions: We observed the patients with reduced urine protein excretion are tends to easier to obtain muscle strengthening. On the other hand, there is a possibility that the patients with increased urine protein excretion are hard to obtain muscle strengthening, during the intervention.