We experienced 1 case of the giant cell tumor of the tendon sheath penetrating the middle phalanx of the third toe. Patient had painless huge mass all around the third phalanx of the foot which made a penetrating hole through the middle phalanx of the third toe in plain radiography. The period from the onset of the symptom until operation was about several years. The mass extended to the base of the distal phalanx and compressed digital nerves and vessels. Patient presented with a chief complaint of the pain on the plantar aspect of the toe and limitation of the motion of the distal interphalangeal joint. Giant cell tumor of the tendon sheath was cured by total en block resection.