Stoma-leakage collecting device, attachment plate and assembly thereof, wherein the collecting device is structured for use together with an ordinary attachment plate for a stoma waste pouch. The collecting device is comprised of a plate-shaped body having a surface which is larger than the surface of the attachment plate. The collecting device comprises an inner, liquid-absorbent material an outer, liquid-tight material and an opening through the outer and inner material, respectively. At least the opening in the outer material is structured for placement around a stoma communication opening in the attachment plate, wherein at least the opening in the outer material is smaller than the smallest transverse dimension of the attachment plate. At least a radially inner rim area located around the opening in the outer material is structured in a manner allowing it to be attached in a liquid-tight manner to a rim area of the attachment plate.
