A 15 months old male pit bull terrier was shown submandibular swelling, which was extended from left submandibular area through mandibular symphysis to right submandibular area and toward around left neck. In history taking, recurrence of swelling was recorded after conservative surgical incision, drainage and dressing. Palpation revealed no pain and heating, partial flutuation and hardness. By paracentesis, it was showed blood-tinged tenacious exudate without bad-smelling. Left submandibular salivary gland was able to be movable freely and the size decreased to half of that of right submandibular salivary gland. It was diagnosed as cervical salivary mucocele. In operation, rostral portion of left sublingual salivary gland was observed to be damaged transversely, showed black color and leaked saliva. Submandibular gland and rostral portion of sublingual salivary gland were resected, after ligation of ducts of submandibular and sublingual salivary glands. At 15 days postoperation, serosanguineous exudate from operation wound was dramatically decreased and stable granulation tissue mass at this area was first palpated. At 39 days after operation, outline of left and right mandibular was appeared normal and skin tenderness of mandibular area was equal to that of the other body wall.