Muscle ultrasound is a useful tool of the neuromuscular disease. On muscle ultrasound, we can detect the affected muscle as increase of muscle echo intensity because of the fibrosis and fatty infiltration. Muscle atrophy and thickened muscle fascia are also visualized with muscle ultrasound. Another advantage of muscle ultrasound compared to other imaging technique is to visualize muscle movement, such as fasciculation. In this paper we review the findings of muscle ultrasound in normal muscle and affected muscle and discuss the possibilities and limitations of muscle ultrasound.