Abstract: The present disclosure relates to an ostomy device for manually controlling the release and collection of bodily waste from an external stoma of a subject. The ostomy device includes a collapsible collecting bag; a first base plate for encircling the stoma; a second base plate having an opening and connected to the collecting bag such that bodily waste can flow through the first base plate and the opening of the second base plate into the collecting bag; a valve for releasing intra-abdominal gas into an exterior of the device; and a cap for closing and for opening the device comprising an inward side for closing onto the second base plate. The valve comprises a valve member for closing the valve, which is openable by pressure applied in a direction towards the subject skin. The present disclosure also relates to an ostomy system including the aforesaid medical device.