A 7-year-old male patient who had abdominal swelling and eyelid oedema was diagnosed with restrictive cardiomyopathy. His serum albumin level was 2.3 g/dl. Protein-losing enteropathy due to restrictive cardiomyopathy was diagnosed and oral budesonide was started. His serum albumin level began to rise and ascites and peripheric oedema disappeared. The patient underwent a successful cardiac transplantation and budesonide was stopped. After the heart transplantation, the albumin level decreased to 2.3 g/dl, and therefore it was restarted. When the serum albumin level increased, the budesonide dose was tapered and stopped in 1 month. Budesonide may be an effective drug in patients with protein-losing enteropathy due to heart failure.