We present a Japanese patient who has congenital muscular dystrophy, with partial merosin deficiency. The patient had characteristic findings of clinical features and brain MRI. Muscle biopsy showed advanced muscular dystrophy, with greatly reduced muscle fibers and massive infiltration of interstitial connective and fatty tissues. On immunostaining for cytoskeletal proteins, merosin was greatly reduced. The other cytoskeletal proteins, including dystrophin and 50 kDa alpha-sarcoglycan were normally expressed around all muscle fibers.