Chronic intestinal pseudo-obstruction(CIPO) is a rare severe digestive disease in which clinical symptoms of intestinal obstruction appear without any mechanical cause. Pathophysiologically, CIPO shows ineffective intestinal propulsion due to an impairment of intestinal smooth muscle, enteric nervous system, and interstitial cells of Cajal(ICC). Sustained increased intra-bowel pressure often causes small intestinal malabsorption and bacterial translocation, and leads to malnutrition and blood stream infection (sepsis). Key points of the medical approach for CIPO are to improve nutritional status and reduce abdominal symptoms. Dietary cure and defecation control are the main options in mild cases, whereas home-parenteral-nutrition(HPN) and decompression therapy are often needed in severe cases. Stimulant laxatives, prokinetics and herbal medicine are usually used but often in fail. Percutaneous endoscopic gastrojejunostomy(PEG-J) tube may be burdenless compared to conventional ileus tube. Most important points in the management of this disease are to make a correct diagnosis as early as possible and avoid unnecessary surgery. However, no clear diagnostic criteria have been established so far. Manometry, scintigraphy, and full-thickness biopsy are the major examination for the CIPO diagnosis in the Western countries; however these specialized examinations are not popular in Japan. Therefore the Research Group(chief investigator, Atsushi Nakajima) proposed Japanese diagnostic criteria in 2009 to facilitate the diagnosis of this rare disease by the general physician. In 2013, we have reported that cine-MRI is a non-invasive diagnostic method for CIPO. Although further data are eagerly awaited, it can become a promising diagnostic tool in CIPO patients. Furthermore the Japanese criteria have been revised, and in 2014, the comprehensive criteria from a child to an adult have been devised. In 2015, CIPO is newly certified as Specified Rare and Intractable Disease which is subsidized from public expense, in Japan. In the future, the diagnostic criteria should be appropriately modified by consultation with additional researchers to make them more practical and internationally applicable.