Central core disease is a rare autosomal dominantly inherited non-progressive congenital myopathy, which is pathologically characterized by the formation of a "core". We report a 28-year-old female with non-progressive muscle weakness, who had a hypotonic posture at birth. The developmental milestones were delayed with her first walking at 18 months of age. She could not run or walk a long distance and weight-bearing tasks were almost impossible. None of her family members showed motor symptoms. An investigation of the electromyography and nerve conduction velocity showed non-specific results. A gastrocnemius muscle biopsy revealed central cores in approximately 70% of myofibers with a type 1 myofiber predominance and deranged sarcolemmal structures. To the best of our knowledge, this is the fifth report of central core disease in the Korean literature.