There is provided a diagnosis system that is capable of allowing general consumers to readily purchase it, as well as capable of measuring defecation gas at home. The present invention is a system (1) including a device (10) on a test subject side, and a server (12), the test subject side device includes a suction device, a gas detector, a test subject identification device, a control device, and a communication device, the server has a database (12a) in which first detection data of odiferous gas, and test subject disease data are accumulated and recorded, and the server side data analyzer is provided with relating means that generates affected test subject defecation gas data, similarity determination means that compares a time-dependent change characteristic of the affected test subject defecation gas data, and a time-dependent change characteristic of test subject defecation gas data.
