Purpose: Swallowing function was in a patient with tongue cancer that was evaluated with video fluorography before and after subtotal glossectomy and reconstruction with a rectus abdominis muscuocutaneous flap. Materials and Methods: A 41-year-old man underwent subtotal glossectomy and retained the unilateral posterior mylohyoid and unilateral stylohyoid muscles. The structure of the flap was evaluated postoperatively. To assess swallowing function, video fluorography was performed before surgery, 1 month after surgery and 1 year after surgery. Testing involved 1) ability to hold 10 mL of liquid in the oral cavity, 2) epiglottis turnover, 3) the presence of aspiration, 4) hyoid bone movement, and 5) maximum width of the esophageal entrance. Results: The flap was protuberant postoperatively. The patient was able to hold the test diet in the oral cavity before and after surgery. Epiglottis turnover was good before surgery but insufficient after surgery. Aspiration during swallowing was not observed before or after surgery. At rest, the hyoid bone sagged postoperatively, in comparison with preoperatively. Hyoid bone movement and width of the esophageal entrance decreased after surgery; however, they demonstrated gradual recovery. Conclusions: For good postoperative swallowing function after subtotal glossectomy, it is necessary to perform reconstruction with protuberant flap and to retain the suprahyoid muscles as much as possible.