A case of appendiceal goblet cell adenocarcinoma (AGCA), which is newly defined in WHO 5th Edition, is reported. An 85-year-old man was referred to our hospital with a positive fecal occult blood test. A series of clinical examinations showed a type 1 tumor at the appendiceal orifice. Signet-ring cell carcinoma was diagnosed by biopsy. Laparoscopically assisted ileocecal resection was then performed. The tumor was first considered a goblet cell carcinoid, but there were some gaps between the histological and immunostaining findings. Finally, it became clear that this tumor should be diagnosed as an AGCA according to the WHO 5th Edition, which is a newly defined subtype of adenocarcinoma. Since malignancy was considered preoperatively, it was possible to perform tumor resection with regional lymph node dissection, although most malignant appendiceal tumors are discovered after appendectomy.