Vitamin D is an important hormone that can be a role of bone and calcium metabolism in the human organ. Thus, vitamin D deficiency could contribute to the severity of metabolic bone disease. The osteomalacia, one of the metabolic bone diseases, is the softening of the bones caused by defective bone mineralization secondary to inadequate amounts of available phosphorus and calcium. We experienced a case of osteomalacia presented with walking disturbance, 30 year-old young aged man, caused by vitamin D deficiency due to strict vegetarian diet and lack of sunlight exposures.