Pseudoaneurysms of the lingual artery are extremely rare. They can be difficult to diagnose and potentially life-threatening. In this report, a case of unusual lingual artery pseudoaneurysm is presented from the standpoint of image diagnosis. A 55-year-old female presented with gradually increasing swelling and pain in the submandibular area. Plain radiograms showed a calcified body surrounding a mass and mandibular erosion. Ultrasonography (US) showed a hypoechoic mass containing pulsatile vessels. Computed tomography (CT) showed a smooth round mass with a combination of an enhancing component and a region of lower attenuation. The latter component was composed of a mixture of high- and low signal intensities in Magnetic Resonance Imaging (MRI), suggesting the presence of coagulation. Angiography revealed limited dilation of the proximal lingual artery. Magnetic resonance angiography (MRA) showed dislocation of carotid arteries but the originating artery was not specified because the dilation of the proximal lingual artery, as revealed by conventional angiography, was limited. Sialography of the submandibular gland showed irreversible degenerative change in the gland due to the aneurysm. The utility of these modalities is discussed.