Background:  Biopsy diagnosis of gastric mucinous carcinoma (GMC) is sometimes difficult. Endoscopic ultrasonography (EUS) can visualize the change in the gastric wall in detail. We reviewed the EUS images and histological findings of cases of GMC and evaluated the correlation between them to identify the characteristic findings of GMC on EUS. Methods:  Thirty‐one GMC patients who had undergone both preoperative EUS and surgery were studied. The EUS images of these patients and the histological findings were compared with those for other histological types of gastric cancer (OGC). Results:  The tumor echo showed high echoic in GMC cases more frequently than that in OGC. The frequency of visualization of the layer structure above the tumor was higher compared with OGC. Histology verified the presence of fine septa composed of thin fibrotic tissue and floating cancer cells in the mucus lake. The mucus lake was often located in the submucosa and the tumor was covered with cancerous mucosa of other histological types with preserved lamina muscularis mucosae. Conclusions:  The EUS findings of GMC are characteristic and reflect its histological changes well, and would complement the preoperative diagnosis of this tumor.