The case is that of a 5-year-old male who was admitted to the hospital for a further examination because of the onset of seizure observed twice. He was delivered at full term by Cesarean section, and had had impairment of movement of his left hand since birth. The results of the first examination performed at the time of his admission to the hospital revealed mild neurological disturbance of the left hand. The CT scanning performed showed partial agenesis of the corpus callosum and a bicameral cyst enhancing the cystic wall extending from the right anterior horn of the lateral ventricle to the body. By MRI sagittal plane, cystic masses presented low signal intensity on the T-1 weighted image, and they showed high signal intensity on the T-2 weighted image. The coronal plane showed that the cysts extended from the midline of the ventricle to the lateral. Cystectomy was performed using the transventricular approach. Thus communication between the cyst and lateral ventricle was made possible. The cystic wall was macroscopically white and elastically soft, and contained vascular components. Histopathologically, it consisted of 3 layers of ciliated cuboidal epithelium, glia cells and connective tissue respectively. We diagnosed the condition as glio-ependymal cyst in the lateral ventricle complicated by partial agenesis of the corpus callosum.