The invention relates to a two-piece ostomy device comprising a base plate for adhering to the skin surrounding a stoma and a releasable collecting bag for collecting output from said stoma. The base plate is releasably connectable to the collecting bag via a first annular flange arranged on the base plate and a second annular flange arranged on the collecting bag. An adhesive is at least partly disposed on at least one of the flanges. The ostomy device further comprises a first through-going hole extending through the first annular flange along a first axis and a second through-going hole extending through the second annular flange along a second axis, wherein the ostomy device further comprises a guiding aid for arranging the first annular flange and the second annular flange in a guiding configuration. In the guiding configuration the movement of the first and the second flange is limited relative to each other in one plane being defined by the first and the second axis and in rotation around at least one of the first or the second axis. The limited movement of the base plate and the collecting bag provides a two-piece system which is easier to apply correctly and thus reduces the risk of leakage.L'invention concerne un dispositif de stomie en deux pièces comprenant une plaque de base (2) destinée à adhérer à la peau entourant un abouchement et un sac de collecte (3) amovible, pour collecter les matières sortant dudit abouchement. La plaque de base peut être connectée au sac de collecte et en être retirée par une première bride annulaire (8) placée sur la plaque de base et une deuxième bride annulaire (14) placée sur le sac de collecte. Le dispositif de stomie peut comprendre en outre un premier trou de passage (7) traversant la première bride annulaire le long d'un premier axe et un deuxième trou de passage (13) traversant la deuxième bride annulaire le long d'un deuxième axe, le dispositif de stomie comprenant en outre une aide de guidage (104) permettant de di
