We report a case of lung metastatic tumor originated from submandibular osteosarcoma, which shows rare advancement and findings. This lung metastatic tumor advanced from left lower lung to left atrium through the left lower pulmonary vein, which penetrated to the left ventricle in the diastolic phase mimicking left atrial myxoma. 67Ga-citrate images showed that hot accumulation were recognized behind the heart in planar image and clear advancement from the lung to the heart in the SPECT image. 67Ga-citrate SPECT image should be available for cardiac tumors.