Endoscopic ultrasonography (EUS) for the diagnosis and staging of early esophageal carcinoma is discussed. Based on the nine-layered structure of esophageal wall, which is in good correspondence with histological layers, depth of carcinoma invasion can be investigated. Ultrasound endoscopes and probes are used for the examination. Ultrasound probes with 20 MHz and 30 MHz transducers can demonstrate the clear images of early esophageal carcinoma by using water filling method, which can discuss the change of the esophageal wall from the surface layer. Although the early esophageal carcinoma is detected by endoscopic findings with or without the dye spraying method by iodine, the diagnosis of depth of carcinoma invasion is not easy. EUS can assist in the diagnosis of depth of carcinoma invasion. Confirming the depth of carcinoma invasion by EUS and the lesion is limited to the mucosa. Endoscopists can decide the indication for endoscopic resection of the lesions.